





Network Working Group                                         R. Danyliw
Request for Comments: 5070                                          CERT
Category: Standards Track                                      J. Meijer
                                                                 UNINETT
                                                            Y. Demchenko
                                                 University of Amsterdam
                                                           December 2007


            The Incident Object Description Exchange Format

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   The Incident Object Description Exchange Format (IODEF) defines a
   data representation that provides a framework for sharing information
   commonly exchanged by Computer Security Incident Response Teams
   (CSIRTs) about computer security incidents.  This document describes
   the information model for the IODEF and provides an associated data
   model specified with XML Schema.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  5
     1.2.  Notations  . . . . . . . . . . . . . . . . . . . . . . . .  5
     1.3.  About the IODEF Data Model . . . . . . . . . . . . . . . .  5
     1.4.  About the IODEF Implementation . . . . . . . . . . . . . .  6
   2.  IODEF Data Types . . . . . . . . . . . . . . . . . . . . . . .  6
     2.1.  Integers . . . . . . . . . . . . . . . . . . . . . . . . .  6
     2.2.  Real Numbers . . . . . . . . . . . . . . . . . . . . . . .  7
     2.3.  Characters and Strings . . . . . . . . . . . . . . . . . .  7
     2.4.  Multilingual Strings . . . . . . . . . . . . . . . . . . .  7
     2.5.  Bytes  . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     2.6.  Hexadecimal Bytes  . . . . . . . . . . . . . . . . . . . .  7
     2.7.  Enumerated Types . . . . . . . . . . . . . . . . . . . . .  8
     2.8.  Date-Time Strings  . . . . . . . . . . . . . . . . . . . .  8







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     2.9.  Timezone String  . . . . . . . . . . . . . . . . . . . . .  8
     2.10. Port Lists . . . . . . . . . . . . . . . . . . . . . . . .  8
     2.11. Postal Address . . . . . . . . . . . . . . . . . . . . . .  9
     2.12. Person or Organization . . . . . . . . . . . . . . . . . .  9
     2.13. Telephone and Fax Numbers  . . . . . . . . . . . . . . . .  9
     2.14. Email String . . . . . . . . . . . . . . . . . . . . . . .  9
     2.15. Uniform Resource Locator strings . . . . . . . . . . . . .  9
   3.  The IODEF Data Model . . . . . . . . . . . . . . . . . . . . .  9
     3.1.  IODEF-Document Class . . . . . . . . . . . . . . . . . . . 10
     3.2.  Incident Class . . . . . . . . . . . . . . . . . . . . . . 10
     3.3.  IncidentID Class . . . . . . . . . . . . . . . . . . . . . 14
     3.4.  AlternativeID Class  . . . . . . . . . . . . . . . . . . . 14
     3.5.  RelatedActivity Class  . . . . . . . . . . . . . . . . . . 15
     3.6.  AdditionalData Class . . . . . . . . . . . . . . . . . . . 16
     3.7.  Contact Class  . . . . . . . . . . . . . . . . . . . . . . 18
       3.7.1.  RegistryHandle Class . . . . . . . . . . . . . . . . . 21
       3.7.2.  PostalAddress Class  . . . . . . . . . . . . . . . . . 22
       3.7.3.  Email Class  . . . . . . . . . . . . . . . . . . . . . 22
       3.7.4.  Telephone and Fax Classes  . . . . . . . . . . . . . . 23
     3.8.  Time Classes . . . . . . . . . . . . . . . . . . . . . . . 23
       3.8.1.  StartTime  . . . . . . . . . . . . . . . . . . . . . . 24
       3.8.2.  EndTime  . . . . . . . . . . . . . . . . . . . . . . . 24
       3.8.3.  DetectTime . . . . . . . . . . . . . . . . . . . . . . 24
       3.8.4.  ReportTime . . . . . . . . . . . . . . . . . . . . . . 24
       3.8.5.  DateTime . . . . . . . . . . . . . . . . . . . . . . . 24
     3.9.  Method Class . . . . . . . . . . . . . . . . . . . . . . . 24
       3.9.1.  Reference Class  . . . . . . . . . . . . . . . . . . . 25
     3.10. Assessment Class . . . . . . . . . . . . . . . . . . . . . 25
       3.10.1. Impact Class . . . . . . . . . . . . . . . . . . . . . 27
       3.10.2. TimeImpact Class . . . . . . . . . . . . . . . . . . . 29
       3.10.3. MonetaryImpact Class . . . . . . . . . . . . . . . . . 30
       3.10.4. Confidence Class . . . . . . . . . . . . . . . . . . . 31
     3.11. History Class  . . . . . . . . . . . . . . . . . . . . . . 32
       3.11.1. HistoryItem Class  . . . . . . . . . . . . . . . . . . 33
     3.12. EventData Class  . . . . . . . . . . . . . . . . . . . . . 34
       3.12.1. Relating the Incident and EventData Classes  . . . . . 36
       3.12.2. Cardinality of EventData . . . . . . . . . . . . . . . 37
     3.13. Expectation Class  . . . . . . . . . . . . . . . . . . . . 37
     3.14. Flow Class . . . . . . . . . . . . . . . . . . . . . . . . 40
     3.15. System Class . . . . . . . . . . . . . . . . . . . . . . . 40
     3.16. Node Class . . . . . . . . . . . . . . . . . . . . . . . . 42
       3.16.1. Counter Class  . . . . . . . . . . . . . . . . . . . . 43
       3.16.2. Address Class  . . . . . . . . . . . . . . . . . . . . 45
       3.16.3. NodeRole Class . . . . . . . . . . . . . . . . . . . . 46
     3.17. Service Class  . . . . . . . . . . . . . . . . . . . . . . 48
       3.17.1. Application Class  . . . . . . . . . . . . . . . . . . 50
     3.18. OperatingSystem Class  . . . . . . . . . . . . . . . . . . 51
     3.19. Record Class . . . . . . . . . . . . . . . . . . . . . . . 51



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       3.19.1. RecordData Class . . . . . . . . . . . . . . . . . . . 51
       3.19.2. RecordPattern Class  . . . . . . . . . . . . . . . . . 53
       3.19.3. RecordItem Class . . . . . . . . . . . . . . . . . . . 54
   4.  Processing Considerations  . . . . . . . . . . . . . . . . . . 54
     4.1.  Encoding . . . . . . . . . . . . . . . . . . . . . . . . . 54
     4.2.  IODEF Namespace  . . . . . . . . . . . . . . . . . . . . . 55
     4.3.  Validation . . . . . . . . . . . . . . . . . . . . . . . . 55
   5.  Extending the IODEF  . . . . . . . . . . . . . . . . . . . . . 56
     5.1.  Extending the Enumerated Values of Attributes  . . . . . . 56
     5.2.  Extending Classes  . . . . . . . . . . . . . . . . . . . . 57
   6.  Internationalization Issues  . . . . . . . . . . . . . . . . . 59
   7.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
     7.1.  Worm . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
     7.2.  Reconnaissance . . . . . . . . . . . . . . . . . . . . . . 61
     7.3.  Bot-Net Reporting  . . . . . . . . . . . . . . . . . . . . 63
     7.4.  Watch List . . . . . . . . . . . . . . . . . . . . . . . . 65
   8.  The IODEF Schema . . . . . . . . . . . . . . . . . . . . . . . 66
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 87
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 88
   11. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 88
   12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 89
     12.1. Normative References . . . . . . . . . . . . . . . . . . . 89
     12.2. Informative References . . . . . . . . . . . . . . . . . . 90




























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1.  Introduction

   Organizations require help from other parties to mitigate malicious
   activity targeting their network and to gain insight into potential
   threats.  This coordination might entail working with an ISP to
   filter attack traffic, contacting a remote site to take down a bot-
   network, or sharing watch-lists of known malicious IP addresses in a
   consortium.

   The Incident Object Description Exchange Format (IODEF) is a format
   for representing computer security information commonly exchanged
   between Computer Security Incident Response Teams (CSIRTs).  It
   provides an XML representation for conveying incident information
   across administrative domains between parties that have an
   operational responsibility of remediation or a watch-and-warning over
   a defined constituency.  The data model encodes information about
   hosts, networks, and the services running on these systems; attack
   methodology and associated forensic evidence; impact of the activity;
   and limited approaches for documenting workflow.

   The overriding purpose of the IODEF is to enhance the operational
   capabilities of CSIRTs.  Community adoption of the IODEF provides an
   improved ability to resolve incidents and convey situational
   awareness by simplifying collaboration and data sharing.  This
   structured format provided by the IODEF allows for:

   o  increased automation in processing of incident data, since the
      resources of security analysts to parse free-form textual
      documents will be reduced;

   o  decreased effort in normalizing similar data (even when highly
      structured) from different sources; and

   o  a common format on which to build interoperable tools for incident
      handling and subsequent analysis, specifically when data comes
      from multiple constituencies.

   Coordinating with other CSIRTs is not strictly a technical problem.
   There are numerous procedural, trust, and legal considerations that
   might prevent an organization from sharing information.  The IODEF
   does not attempt to address them.  However, operational
   implementations of the IODEF will need to consider this broader
   context.

   Sections 3 and 8 specify the IODEF data model with text and an XML
   schema.  The types used by the data model are covered in Section 2.
   Processing considerations, the handling of extensions, and
   internationalization issues related to the data model are covered in



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   Sections 4, 5, and 6, respectively.  Examples are listed in Section
   7.  Section 1 provides the background for the IODEF, and Section 9
   documents the security considerations.

1.1.  Terminology

   The key words "MUST," "MUST NOT," "REQUIRED," "SHALL," "SHALL NOT,"
   "SHOULD," "SHOULD NOT," "RECOMMENDED," "MAY," and "OPTIONAL" in this
   document are to be interpreted as described in RFC2119 [6].

   Definitions for some of the common computer security-related
   terminology used in this document can be found in Section 2 of [16].

1.2.  Notations

   The normative IODEF data model is specified with the text in Section
   3 and the XML schema in Section 8.  To help in the understanding of
   the data elements, Section 3 also depicts the underlying information
   model using Unified Modeling Language (UML).  This abstract
   presentation of the IODEF is not normative.

   For clarity in this document, the term "XML document" will be used
   when referring generically to any instance of an XML document.  The
   term "IODEF document" will be used to refer to specific elements and
   attributes of the IODEF schema.  The terms "class" and "element" will
   be used interchangeably to reference either the corresponding data
   element in the information or data models, respectively.

1.3.  About the IODEF Data Model

   The IODEF data model is a data representation that provides a
   framework for sharing information commonly exchanged by CSIRTs about
   computer security incidents.  A number of considerations were made in
   the design of the data model.

   o  The data model serves as a transport format.  Therefore, its
      specific representation is not the optimal representation for on-
      disk storage, long-term archiving, or in-memory processing.

   o  As there is no precise widely agreed upon definition for an
      incident, the data model does not attempt to dictate one through
      its implementation.  Rather, a broad understanding is assumed in
      the IODEF that is flexible enough to encompass most operators.

   o  Describing an incident for all definitions would require an
      extremely complex data model.  Therefore, the IODEF only intends
      to be a framework to convey commonly exchanged incident
      information.  It ensures that there are ample mechanisms for



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      extensibility to support organization-specific information, and
      techniques to reference information kept outside of the explicit
      data model.

   o  The domain of security analysis is not fully standardized and must
      rely on free-form textual descriptions.  The IODEF attempts to
      strike a balance between supporting this free-form content, while
      still allowing automated processing of incident information.

   o  The IODEF is only one of several security relevant data
      representations being standardized.  Attempts were made to ensure
      they were complimentary.  The data model of the Intrusion
      Detection Message Exchange Format [17] influenced the design of
      the IODEF.

   Further discussion of the desirable properties for the IODEF can be
   found in the Requirements for the Format for Incident Information
   Exchange (FINE) [16].

1.4.  About the IODEF Implementation

   The IODEF implementation is specified as an Extensible Markup
   Language (XML) [1] Schema [2] in Section 8.

   Implementing the IODEF in XML provides numerous advantages.  Its
   extensibility makes it ideal for specifying a data encoding framework
   that supports various character encodings.  Likewise, the abundance
   of related technologies (e.g., XSL, XPath, XML-Signature) makes for
   simplified manipulation.  However, XML is fundamentally a text
   representation, which makes it inherently inefficient when binary
   data must be embedded or large volumes of data must be exchanged.

2.  IODEF Data Types

   The various data elements of the IODEF data model are typed.  This
   section discusses these data types.  When possible, native Schema
   data types were adopted, but for more complicated formats, regular
   expressions (see Appendix F of [3]) or external standards were used.

2.1.  Integers

   An integer is represented by the INTEGER data type.  Integer data
   MUST be encoded in Base 10.

   The INTEGER data type is implemented as an "xs:integer" [3] in the
   schema.





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2.2.  Real Numbers

   Real (floating-point) attributes are represented by the REAL data
   type.  Real data MUST be encoded in Base 10.

   The REAL data type is implemented as an "xs:float" [3] in the schema.

2.3.  Characters and Strings

   A single character is represented by the CHARACTER data type.  A
   character string is represented by the STRING data type.  Special
   characters must be encoded using entity references.  See Section 4.1.

   The CHARACTER and STRING data types are implement as an "xs:string"
   [3] in the schema.

2.4.  Multilingual Strings

   STRING data that represents multi-character attributes in a language
   different than the default encoding of the document is of the
   ML_STRING data type.

   The ML_STRING data type is implemented as an "iodef:MLStringType" in
   the schema.

2.5.  Bytes

   A binary octet is represented by the BYTE data type.  A sequence of
   binary octets is represented by the BYTE[] data type.  These octets
   are encoded using base64.

   The BYTE data type is implemented as an "xs:base64Binary" [3] in the
   schema.

2.6.  Hexadecimal Bytes

   A binary octet is represented by the HEXBIN (and HEXBIN[]) data type.
   This octet is encoded as a character tuple consisting of two
   hexadecimal digits.

   The HEXBIN data type is implemented as an "xs:hexBinary" [3] in the
   schema.









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2.7.  Enumerated Types

   Enumerated types are represented by the ENUM data type, and consist
   of an ordered list of acceptable values.  Each value has a
   representative keyword.  Within the IODEF schema, the enumerated type
   keywords are used as attribute values.

   The ENUM data type is implemented as a series of "xs:NMTOKEN" in the
   schema.

2.8.  Date-Time Strings

   Date-time strings are represented by the DATETIME data type.  Each
   date-time string identifies a particular instant in time; ranges are
   not supported.

   Date-time strings are formatted according to a subset of ISO 8601:
   2000 [13] documented in RFC 3339 [12].

   The DATETIME data type is implemented as an "xs:dateTime" [3] in the
   schema.

2.9.  Timezone String

   A timezone offset from UTC is represented by the TIMEZONE data type.
   It is formatted according to the following regular expression:
   "Z|[\+\-](0[0-9]|1[0-4]):[0-5][0-9]".

   The TIMEZONE data type is implemented as an "xs:string" with a
   regular expression constraint in the schema.  This regular expression
   is identical to the timezone representation implemented in an "xs:
   dateTime".

2.10.  Port Lists

   A list of network ports are represented by the PORTLIST data type.  A
   PORTLIST consists of a comma-separated list of numbers and ranges
   (N-M means ports N through M, inclusive).  It is formatted according
   to the following regular expression: "\d+(\-\d+)?(,\d+(\-\d+)?)*".
   For example, "2,5-15,30,32,40-50,55-60".

   The PORTLIST data type is implemented as an "xs:string" with a
   regular expression constraint in the schema.








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2.11.  Postal Address

   A postal address is represented by the POSTAL data type.  This data
   type is an ML_STRING whose format is documented in Section 2.23 of
   RFC 4519 [10].  It defines a postal address as a free-form multi-line
   string separated by the "$" character.

   The POSTAL data type is implemented as an "xs:string" in the schema.

2.12.  Person or Organization

   The name of an individual or organization is represented by the NAME
   data type.  This data type is an ML_STRING whose format is documented
   in Section 2.3 of RFC 4519 [10].

   The NAME data type is implemented as an "xs:string" in the schema.

2.13.  Telephone and Fax Numbers

   A telephone or fax number is represented by the PHONE data type.  The
   format of the PHONE data type is documented in Section 2.35 of RFC
   4519 [10].

   The PHONE data type is implemented as an "xs:string" in the schema.

2.14.  Email String

   An email address is represented by the EMAIL data type.  The format
   of the EMAIL data type is documented in Section 3.4.1 RFC 2822 [11]

   The EMAIL data type is implemented as an "xs:string" in the schema.

2.15.  Uniform Resource Locator strings

   A uniform resource locator (URL) is represented by the URL data type.
   The format of the URL data type is documented in RFC 2396 [8].

   The URL data type is implemented as an "xs:anyURI" in the schema.

3.  The IODEF Data Model

   In this section, the individual components of the IODEF data model
   will be discussed in detail.  For each class, the semantics will be
   described and the relationship with other classes will be depicted
   with UML.  When necessary, specific comments will be made about
   corresponding definition in the schema in Section 8





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3.1.  IODEF-Document Class

   The IODEF-Document class is the top level class in the IODEF data
   model.  All IODEF documents are an instance of this class.

   +-----------------+
   | IODEF-Document  |
   +-----------------+
   | STRING version  |<>--{1..*}--[ Incident     ]
   | ENUM lang       |
   | STRING formatid |
   +-----------------+

                      Figure 1: IODEF-Document Class

   The aggregate class that constitute IODEF-Document is:

   Incident
      One or more.  The information related to a single incident.

   The IODEF-Document class has three attributes:

   version
      Required.  STRING.  The IODEF specification version number to
      which this IODEF document conforms.  The value of this attribute
      MUST be "1.00"

   lang
      Required.  ENUM.  A valid language code per RFC 4646 [7]
      constrained by the definition of "xs:language".  The
      interpretation of this code is described in Section 6.

   formatid
      Optional.  STRING.  A free-form string to convey processing
      instructions to the recipient of the document.  Its semantics must
      be negotiated out-of-band.

3.2.  Incident Class

   Every incident is represented by an instance of the Incident class.
   This class provides a standardized representation for commonly
   exchanged incident data.









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   +--------------------+
   | Incident           |
   +--------------------+
   | ENUM purpose       |<>----------[ IncidentID      ]
   | STRING ext-purpose |<>--{0..1}--[ AlternativeID   ]
   | ENUM lang          |<>--{0..1}--[ RelatedActivity ]
   | ENUM restriction   |<>--{0..1}--[ DetectTime      ]
   |                    |<>--{0..1}--[ StartTime       ]
   |                    |<>--{0..1}--[ EndTime         ]
   |                    |<>----------[ ReportTime      ]
   |                    |<>--{0..*}--[ Description     ]
   |                    |<>--{1..*}--[ Assessment      ]
   |                    |<>--{0..*}--[ Method          ]
   |                    |<>--{1..*}--[ Contact         ]
   |                    |<>--{0..*}--[ EventData       ]
   |                    |<>--{0..1}--[ History         ]
   |                    |<>--{0..*}--[ AdditionalData  ]
   +--------------------+

                       Figure 2: The Incident Class

   The aggregate classes that constitute Incident are:

   IncidentID
      One. An incident tracking number assigned to this incident by the
      CSIRT that generated the IODEF document.

   AlternativeID
      Zero or one.  The incident tracking numbers used by other CSIRTs
      to refer to the incident described in the document.

   RelatedActivity
      Zero or one.  The incident tracking numbers of related incidents.

   DetectTime
      Zero or one.  The time the incident was first detected.

   StartTime
      Zero or one.  The time the incident started.

   EndTime
      Zero or one.  The time the incident ended.

   ReportTime
      One. The time the incident was reported.






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   Description
      Zero or more.  ML_STRING.  A free-form textual description of the
      incident.

   Assessment
      One or more.  A characterization of the impact of the incident.

   Method
      Zero or more.  The techniques used by the intruder in the
      incident.

   Contact
      One or more.  Contact information for the parties involved in the
      incident.

   EventData
      Zero or more.  Description of the events comprising the incident.

   History
      Zero or one.  A log of significant events or actions that occurred
      during the course of handling the incident.

   AdditionalData
      Zero or more.  Mechanism by which to extend the data model.

   The Incident class has four attributes:

   purpose
      Required.  ENUM.  The purpose attribute represents the reason why
      the IODEF document was created.  It is closely related to the
      Expectation class (Section 3.13).  This attribute is defined as an
      enumerated list:

      1.  traceback.  The document was sent for trace-back purposes.

      2.  mitigation.  The document was sent to request aid in
          mitigating the described activity.

      3.  reporting.  The document was sent to comply with reporting
          requirements.

      4.  other.  The document was sent for purposes specified in the
          Expectation class.

      5.  ext-value.  An escape value used to extend this attribute.
          See Section 5.1.





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   ext-purpose
      Optional.  STRING.  A means by which to extend the purpose
      attribute.  See Section 5.1.

   lang
      Optional.  ENUM.  A valid language code per RFC 4646 [7]
      constrained by the definition of "xs:language".  The
      interpretation of this code is described in Section 6.

   restriction
      Optional.  ENUM.  This attribute indicates the disclosure
      guidelines to which the sender expects the recipient to adhere for
      the information represented in this class and its children.  This
      guideline provides no security since there are no specified
      technical means to ensure that the recipient of the document
      handles the information as the sender requested.

      The value of this attribute is logically inherited by the children
      of this class.  That is to say, the disclosure rules applied to
      this class, also apply to its children.

      It is possible to set a granular disclosure policy, since all of
      the high-level classes (i.e., children of the Incident class) have
      a restriction attribute.  Therefore, a child can override the
      guidelines of a parent class, be it to restrict or relax the
      disclosure rules (e.g., a child has a weaker policy than an
      ancestor; or an ancestor has a weak policy, and the children
      selectively apply more rigid controls).  The implicit value of the
      restriction attribute for a class that did not specify one can be
      found in the closest ancestor that did specify a value.

      This attribute is defined as an enumerated value with a default
      value of "private".  Note that the default value of the
      restriction attribute is only defined in the context of the
      Incident class.  In other classes where this attribute is used, no
      default is specified.

      1.  public.  There are no restrictions placed in the information.

      2.  need-to-know.  The information may be shared with other
          parties that are involved in the incident as determined by the
          recipient of this document (e.g., multiple victim sites can be
          informed of each other).

      3.  private.  The information may not be shared.






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      4.  default.  The information can be shared according to an
          information disclosure policy pre-arranged by the
          communicating parties.

3.3.  IncidentID Class

   The IncidentID class represents an incident tracking number that is
   unique in the context of the CSIRT and identifies the activity
   characterized in an IODEF Document.  This identifier would serve as
   an index into the CSIRT incident handling system.  The combination of
   the name attribute and the string in the element content MUST be a
   globally unique identifier describing the activity.  Documents
   generated by a given CSIRT MUST NOT reuse the same value unless they
   are referencing the same incident.

   +------------------+
   | IncidentID       |
   +------------------+
   | STRING           |
   |                  |
   | STRING name      |
   | STRING instance  |
   | ENUM restriction |
   +------------------+

                      Figure 3: The IncidentID Class

   The IncidentID class has three attributes:

   name
      Required.  STRING.  An identifier describing the CSIRT that
      created the document.  In order to have a globally unique CSIRT
      name, the fully qualified domain name associated with the CSIRT
      MUST be used.

   instance
      Optional.  STRING.  An identifier referencing a subset of the
      named incident.

   restriction
      Optional.  ENUM.  This attribute has been defined in Section 3.2.

3.4.  AlternativeID Class

   The AlternativeID class lists the incident tracking numbers used by
   CSIRTs, other than the one generating the document, to refer to the
   identical activity described the IODEF document.  A tracking number
   listed as an AlternativeID references the same incident detected by



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   another CSIRT.  The incident tracking numbers of the CSIRT that
   generated the IODEF document should never be considered an
   AlternativeID.

         +------------------+
         | AlternativeID    |
         +------------------+
         | ENUM restriction |<>--{1..*}--[ IncidentID ]
         |                  |
         +------------------+

                     Figure 4: The AlternativeID Class

   The aggregate class that constitutes AlternativeID is:

   IncidentID
      One or more.  The incident tracking number of another CSIRT.

   The AlternativeID class has one attribute:

   restriction
      Optional.  ENUM.  This attribute has been defined in Section 3.2.

3.5.  RelatedActivity Class

   The RelatedActivity class lists either incident tracking numbers of
   incidents or URLs (not both) that refer to activity related to the
   one described in the IODEF document.  These references may be to
   local incident tracking numbers or to those of other CSIRTs.

   The specifics of how a CSIRT comes to believe that two incidents are
   related are considered out of scope.

         +------------------+
         | RelatedActivity  |
         +------------------+
         | ENUM restriction |<>--{0..*}--[ IncidentID ]
         |                  |<>--{0..*}--[ URL        ]
         +------------------+

                      Figure 5: RelatedActivity Class










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   The aggregate classes that constitutes RelatedActivity are:

   IncidentID
      One or more.  The incident tracking number of a related incident.

   URL
      One or more.  URL.  A URL to activity related to this incident.

   The RelatedActivity class has one attribute:

   restriction
      Optional.  ENUM.  This attribute has been defined in Section 3.2.

3.6.  AdditionalData Class

   The AdditionalData class serves as an extension mechanism for
   information not otherwise represented in the data model.  For
   relatively simple information, atomic data types (e.g., integers,
   strings) are provided with a mechanism to annotate their meaning.
   The class can also be used to extend the data model (and the
   associated Schema) to support proprietary extensions by encapsulating
   entire XML documents conforming to another Schema (e.g., IDMEF).  A
   detailed discussion for extending the data model and the schema can
   be found in Section 5.

   Unlike XML, which is self-describing, atomic data must be documented
   to convey its meaning.  This information is described in the
   'meaning' attribute.  Since these description are outside the scope
   of the specification, some additional coordination may be required to
   ensure that a recipient of a document using the AdditionalData
   classes can make sense of the custom extensions.

   +------------------+
   | AdditionalData   |
   +------------------+
   | ANY              |
   |                  |
   | ENUM dtype       |
   | STRING ext-dtype |
   | STRING meaning   |
   | STRING formatid  |
   | ENUM restriction |
   +------------------+

                    Figure 6: The AdditionalData Class






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   The AdditionalData class has five attributes:

   dtype
      Required.  ENUM.  The data type of the element content.  The
      permitted values for this attribute are shown below.  The default
      value is "string".

      1.   boolean.  The element content is of type BOOLEAN.

      2.   byte.  The element content is of type BYTE.

      3.   character.  The element content is of type CHARACTER.

      4.   date-time.  The element content is of type DATETIME.

      5.   integer.  The element content is of type INTEGER.

      6.   portlist.  The element content is of type PORTLIST.

      7.   real.  The element content is of type REAL.

      8.   string.  The element content is of type STRING.

      9.   file.  The element content is a base64 encoded binary file
           encoded as a BYTE[] type.

      10.  frame.  The element content is a layer-2 frame encoded as a
           HEXBIN type.

      11.  packet.  The element content is a layer-3 packet encoded as a
           HEXBIN type.

      12.  ipv4-packet.  The element content is an IPv4 packet encoded
           as a HEXBIN type.

      13.  ipv6-packet.  The element content is an IPv6 packet encoded
           as a HEXBIN type.

      14.  path.  The element content is a file-system path encoded as a
           STRING type.

      15.  url.  The element content is of type URL.

      16.  csv.  The element content is a common separated value (CSV)
           list per Section 2 of [20] encoded as a STRING type.

      17.  winreg.  The element content is a Windows registry key
           encoded as a STRING type.



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      18.  xml.  The element content is XML (see Section 5).

      19.  ext-value.  An escape value used to extend this attribute.
           See Section 5.1.

   ext-dtype
      Optional.  STRING.  A means by which to extend the dtype
      attribute.  See Section 5.1.

   meaning
      Optional.  STRING.  A free-form description of the element
      content.

   formatid
      Optional.  STRING.  An identifier referencing the format and
      semantics of the element content.

   restriction
      Optional.  ENUM.  This attribute has been defined in Section 3.2.

3.7.  Contact Class

   The Contact class describes contact information for organizations and
   personnel involved in the incident.  This class allows for the naming
   of the involved party, specifying contact information for them, and
   identifying their role in the incident.

   People and organizations are treated interchangeably as contacts; one
   can be associated with the other using the recursive definition of
   the class (the Contact class is aggregated into the Contact class).
   The 'type' attribute disambiguates the type of contact information
   being provided.

   The inheriting definition of Contact provides a way to relate
   information without requiring the explicit use of identifiers in the
   classes or duplication of data.  A complete point of contact is
   derived by a particular traversal from the root Contact class to the
   leaf Contact class.  As such, multiple points of contact might be
   specified in a single instance of a Contact class.  Each child
   Contact class logically inherits contact information from its
   ancestors.










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   +------------------+
   | Contact          |
   +------------------+
   | ENUM role        |<>--{0..1}--[ ContactName    ]
   | STRING ext-role  |<>--{0..*}--[ Description    ]
   | ENUM type        |<>--{0..*}--[ RegistryHandle ]
   | STRING ext-type  |<>--{0..1}--[ PostalAddress  ]
   | ENUM restriction |<>--{0..*}--[ Email          ]
   |                  |<>--{0..*}--[ Telephone      ]
   |                  |<>--{0..1}--[ Fax            ]
   |                  |<>--{0..1}--[ Timezone       ]
   |                  |<>--{0..*}--[ Contact        ]
   |                  |<>--{0..*}--[ AdditionalData ]
   +------------------+

                        Figure 7: The Contact Class

   The aggregate classes that constitute the Contact class are:

   ContactName
      Zero or one.  ML_STRING.  The name of the contact.  The contact
      may either be an organization or a person.  The type attribute
      disambiguates the semantics.

   Description
      Zero or many.  ML_STRING.  A free-form description of this
      contact.  In the case of a person, this is often the
      organizational title of the individual.

   RegistryHandle
      Zero or many.  A handle name into the registry of the contact.

   PostalAddress
      Zero or one.  The postal address of the contact.

   Email
      Zero or many.  The email address of the contact.

   Telephone
      Zero or many.  The telephone number of the contact.

   Fax
      Zero or one.  The facsimile telephone number of the contact.

   Timezone
      Zero or one.  TIMEZONE.  The timezone in which the contact resides
      formatted according to Section 2.9.




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   Contact
      Zero or many.  A Contact instance contained within another Contact
      instance inherits the values of the parent(s).  This recursive
      definition can be used to group common data pertaining to multiple
      points of contact and is especially useful when listing multiple
      contacts at the same organization.

   AdditionalData
      Zero or many.  A mechanism by which to extend the data model.

   At least one of the aggregate classes MUST be present in an instance
   of the Contact class.  This is not enforced in the IODEF schema as
   there is no simple way to accomplish it.

   The Contact class has five attributes:

   role
      Required.  ENUM.  Indicates the role the contact fulfills.  This
      attribute is defined as an enumerated list:

      1.  creator.  The entity that generate the document.

      2.  admin.  An administrative contact for a host or network.

      3.  tech.  A technical contact for a host or network.

      4.  irt.  The CSIRT involved in handling the incident.

      5.  cc.  An entity that is to be kept informed about the handling
          of the incident.

      6.  ext-value.  An escape value used to extend this attribute.
          See Section 5.1.

   ext-role
      Optional.  STRING.  A means by which to extend the role attribute.
      See Section 5.1.

   type
      Required.  ENUM.  Indicates the type of contact being described.
      This attribute is defined as an enumerated list:

      1.  person.  The information for this contact references an
          individual.

      2.  organization.  The information for this contact references an
          organization.




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      3.  ext-value.  An escape value used to extend this attribute.
          See Section 5.1.

   ext-type
      Optional.  STRING.  A means by which to extend the type attribute.
      See Section 5.1.

   restriction
      Optional.  ENUM.  This attribute is defined in Section 3.2.

3.7.1.  RegistryHandle Class

   The RegistryHandle class represents a handle into an Internet
   registry or community-specific database.  The handle is specified in
   the element content and the type attribute specifies the database.

   +---------------------+
   | RegistryHandle      |
   +---------------------+
   | STRING              |
   |                     |
   | ENUM registry       |
   | STRING ext-registry |
   +---------------------+

                    Figure 8: The RegistryHandle Class

   The RegistryHandle class has two attributes:

   registry
      Required.  ENUM.  The database to which the handle belongs.  The
      default value is 'local'.  The possible values are:

      1.  internic.  Internet Network Information Center

      2.  apnic.  Asia Pacific Network Information Center

      3.  arin.  American Registry for Internet Numbers

      4.  lacnic.  Latin-American and Caribbean IP Address Registry

      5.  ripe.  Reseaux IP Europeens

      6.  afrinic.  African Internet Numbers Registry

      7.  local.  A database local to the CSIRT





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      8.  ext-value.  An escape value used to extend this attribute.
          See Section 5.1.

   ext-registry
      Optional.  STRING.  A means by which to extend the registry
      attribute.  See Section 5.1.

3.7.2.  PostalAddress Class

   The PostalAddress class specifies a postal address formatted
   according to the POSTAL data type (Section 2.11).

   +---------------------+
   | PostalAddress       |
   +---------------------+
   | POSTAL              |
   |                     |
   | ENUM meaning        |
   | ENUM lang           |
   +---------------------+

                     Figure 9: The PostalAddress Class

   The PostalAddress class has two attributes:

   meaning
      Optional.  ENUM.  A free-form description of the element content.

   lang
      Required.  ENUM.  A valid language code per RFC 4646 [7]
      constrained by the definition of "xs:language".  The
      interpretation of this code is described in Section 6.

3.7.3.  Email Class

   The Email class specifies an email address formatted according to
   EMAIL data type (Section 2.14).

   +--------------+
   | Email        |
   +--------------+
   | EMAIL        |
   |              |
   | ENUM meaning |
   +--------------+

                        Figure 10: The Email Class




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   The Email class has one attribute:

   meaning
      Optional.  ENUM.  A free-form description of the element content.

3.7.4.  Telephone and Fax Classes

   The Telephone and Fax classes specify a voice or fax telephone number
   respectively, and are formatted according to PHONE data type
   (Section 2.13).

   +--------------------+
   | {Telephone | Fax } |
   +--------------------+
   | PHONE              |
   |                    |
   | ENUM meaning       |
   +--------------------+

                 Figure 11: The Telephone and Fax Classes

   The Telephone class has one attribute:

   meaning
      Optional.  ENUM.  A free-form description of the element content
      (e.g., hours of coverage for a given number).

3.8.  Time Classes

   The data model uses five different classes to represent a timestamp.
   Their definition is identical, but each has a distinct name to convey
   a difference in semantics.

   The element content of each class is a timestamp formatted according
   to the DATETIME data type (see Section 2.8).

   +----------------------------------+
   | {Start| End| Report| Detect}Time |
   +----------------------------------+
   | DATETIME                         |
   +----------------------------------+

                        Figure 12: The Time Classes








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3.8.1.  StartTime

   The StartTime class represents the time the incident began.

3.8.2.  EndTime

   The EndTime class represents the time the incident ended.

3.8.3.  DetectTime

   The DetectTime class represents the time the first activity of the
   incident was detected.

3.8.4.  ReportTime

   The ReportTime class represents the time the incident was reported.
   This timestamp SHOULD coincide to the time at which the IODEF
   document is generated.

3.8.5.  DateTime

   The DateTime class is a generic representation of a timestamp.  Its
   semantics should be inferred from the parent class in which it is
   aggregated.

3.9.  Method Class

   The Method class describes the methodology used by the intruder to
   perpetrate the events of the incident.  This class consists of a list
   of references describing the attack method and a free form
   description of the technique.

   +------------------+
   | Method           |
   +------------------+
   | ENUM restriction |<>--{0..*}--[ Reference      ]
   |                  |<>--{0..*}--[ Description    ]
   |                  |<>--{0..*}--[ AdditionalData ]
   +------------------+

                        Figure 13: The Method Class

   The Method class is composed of three aggregate classes.

   Reference
      Zero or many.  A reference to a vulnerability, malware sample,
      advisory, or analysis of an attack technique.




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   Description
      Zero or many.  ML_STRING.  A free-form text description of the
      methodology used by the intruder.

   AdditionalData
      Zero or many.  A mechanism by which to extend the data model.

   Either an instance of the Reference or Description class MUST be
   present.

   The Method class has one attribute:

   restriction
      Optional.  ENUM.  This attribute is defined in Section 3.2.

3.9.1.  Reference Class

   The Reference class is a reference to a vulnerability, IDS alert,
   malware sample, advisory, or attack technique.  A reference consists
   of a name, a URL to this reference, and an optional description.

   +------------------+
   | Reference        |
   +------------------+
   |                  |<>----------[ ReferenceName ]
   |                  |<>--{0..*}--[ URL           ]
   |                  |<>--{0..*}--[ Description   ]
   +------------------+

                      Figure 14: The Reference Class

   The aggregate classes that constitute Reference:

   ReferenceName
      One. ML_STRING.  Name of the reference.

   URL
      Zero or many.  URL.  A URL associated with the reference.

   Description
      Zero or many.  ML_STRING.  A free-form text description of this
      reference.

3.10.  Assessment Class

   The Assessment class describes the technical and non-technical
   repercussions of the incident on the CSIRT's constituency.




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   This class was derived from the IDMEF[17].

    +------------------+
    | Assessment       |
    +------------------+
    | ENUM occurrence  |<>--{0..*}--[ Impact         ]
    | ENUM restriction |<>--{0..*}--[ TimeImpact     ]
    |                  |<>--{0..*}--[ MonetaryImpact ]
    |                  |<>--{0..*}--[ Counter        ]
    |                  |<>--{0..1}--[ Confidence     ]
    |                  |<>--{0..*}--[ AdditionalData ]
    +------------------+

                        Figure 15: Assessment Class

   The aggregate classes that constitute Assessment are:

   Impact
      Zero or many.  Technical impact of the incident on a network.

   TimeImpact
      Zero or many.  Impact of the activity measured with respect to
      time.

   MonetaryImpact
      Zero or many.  Impact of the activity measured with respect to
      financial loss.

   Counter
      Zero or more.  A counter with which to summarize the magnitude of
      the activity.

   Confidence
      Zero or one.  An estimate of confidence in the assessment.

   AdditionalData
      Zero or many.  A mechanism by which to extend the data model.

   A least one instance of the possible three impact classes (i.e.,
   Impact, TimeImpact, or MonetaryImpact) MUST be present.

   The Assessment class has two attributes:

   occurrence
      Optional.  ENUM.  Specifies whether the assessment is describing
      actual or potential outcomes.  The default is "actual" and is
      assumed if not specified.




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      1.  actual.  This assessment describes activity that has occurred.

      2.  potential.  This assessment describes potential activity that
          might occur.

   restriction
      Optional.  ENUM.  This attribute is defined in Section 3.2.

3.10.1.  Impact Class

   The Impact class allows for categorizing and describing the technical
   impact of the incident on the network of an organization.

   This class is based on the IDMEF [17].

   +------------------+
   | Impact           |
   +------------------+
   | ML_STRING        |
   |                  |
   | ENUM lang        |
   | ENUM severity    |
   | ENUM completion  |
   | ENUM type        |
   | STRING ext-type  |
   +------------------+

                          Figure 16: Impact Class

   The element content will be a free-form textual description of the
   impact.

   The Impact class has five attributes:

   lang
      Required.  ENUM.  A valid language code per RFC 4646 [7]
      constrained by the definition of "xs:language".  The
      interpretation of this code is described in Section 6.

   severity
      Optional.  ENUM.  An estimate of the relative severity of the
      activity.  The permitted values are shown below.  There is no
      default value.








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      1.  low.  Low severity

      2.  medium.  Medium severity

      3.  high.  High severity

   completion
      Optional.  ENUM.  An indication whether the described activity was
      successful.  The permitted values are shown below.  There is no
      default value.

      1.  failed.  The attempted activity was not successful.

      2.  succeeded.  The attempted activity succeeded.

   type
      Required.  ENUM.  Classifies the malicious activity into incident
      categories.  The permitted values are shown below.  The default
      value is "other".

      1.   admin.  Administrative privileges were attempted.

      2.   dos.  A denial of service was attempted.

      3.   file.  An action that impacts the integrity of a file or
           database was attempted.

      4.   info-leak.  An attempt was made to exfiltrate information.

      5.   misconfiguration.  An attempt was made to exploit a mis-
           configuration in a system.

      6.   policy.  Activity violating site's policy was attempted.

      7.   recon.  Reconnaissance activity was attempted.

      8.   social-engineering.  A social engineering attack was
           attempted.

      9.   user.  User privileges were attempted.

      10.  unknown.  The classification of this activity is unknown.

      11.  ext-value.  An escape value used to extend this attribute.
           See Section 5.1.






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   ext-type
      Optional.  STRING.  A means by which to extend the type attribute.
      See Section 5.1.

3.10.2.  TimeImpact Class

   The TimeImpact class describes the impact of the incident on an
   organization as a function of time.  It provides a way to convey down
   time and recovery time.

         +---------------------+
         | TimeImpact          |
         +---------------------+
         | REAL                |
         |                     |
         | ENUM severity       |
         | ENUM metric         |
         | STRING ext-metric   |
         | ENUM duration       |
         | STRING ext-duration |
         +---------------------+

                        Figure 17: TimeImpact Class

   The element content is a positive, floating point (REAL) number
   specifying a unit of time.  The duration and metric attributes will
   imply the semantics of the element content.

   The TimeImpact class has five attributes:

   severity
      Optional.  ENUM.  An estimate of the relative severity of the
      activity.  The permitted values are shown below.  There is no
      default value.

      1.  low.  Low severity

      2.  medium.  Medium severity

      3.  high.  High severity

   metric
      Required.  ENUM.  Defines the metric in which the time is
      expressed.  The permitted values are shown below.  There is no
      default value.






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      1.  labor.  Total staff-time to recovery from the activity (e.g.,
          2 employees working 4 hours each would be 8 hours).

      2.  elapsed.  Elapsed time from the beginning of the recovery to
          its completion (i.e., wall-clock time).

      3.  downtime.  Duration of time for which some provided service(s)
          was not available.

      4.  ext-value.  An escape value used to extend this attribute.
          See Section 5.1.

   ext-metric
      Optional.  STRING.  A means by which to extend the metric
      attribute.  See Section 5.1.

   duration
      Required.  ENUM.  Defines a unit of time, that when combined with
      the metric attribute, fully describes a metric of impact that will
      be conveyed in the element content.  The permitted values are
      shown below.  The default value is "hour".

      1.  second.  The unit of the element content is seconds.

      2.  minute.  The unit of the element content is minutes.

      3.  hour.  The unit of the element content is hours.

      4.  day.  The unit of the element content is days.

      5.  month.  The unit of the element content is months.

      6.  quarter.  The unit of the element content is quarters.

      7.  year.  The unit of the element content is years.

      8.  ext-value.  An escape value used to extend this attribute.
          See Section 5.1.

   ext-duration
      Optional.  STRING.  A means by which to extend the duration
      attribute.  See Section 5.1.

3.10.3.  MonetaryImpact Class

   The MonetaryImpact class describes the financial impact of the
   activity on an organization.  For example, this impact may consider
   losses due to the cost of the investigation or recovery, diminished



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   productivity of the staff, or a tarnished reputation that will affect
   future opportunities.

         +------------------+
         | MonetaryImpact   |
         +------------------+
         | REAL             |
         |                  |
         | ENUM severity    |
         | STRING currency  |
         +------------------+

                      Figure 18: MonetaryImpact Class

   The element content is a positive, floating point number (REAL)
   specifying a unit of currency described in the currency attribute.

   The MonetaryImpact class has two attributes:

   severity
      Optional.  ENUM.  An estimate of the relative severity of the
      activity.  The permitted values are shown below.  There is no
      default value.

      1.  low.  Low severity

      2.  medium.  Medium severity

      3.  high.  High severity

   currency
      Required.  STRING.  Defines the currency in which the monetary
      impact is expressed.  The permitted values are defined in ISO
      4217:2001, Codes for the representation of currencies and funds
      [14].  There is no default value.

3.10.4.  Confidence Class

   The Confidence class represents a best estimate of the validity and
   accuracy of the described impact (see Section 3.10) of the incident
   activity.  This estimate can be expressed as a category or a numeric
   calculation.

   This class if based upon the IDMEF [17]).







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         +------------------+
         | Confidence       |
         +------------------+
         | REAL             |
         |                  |
         | ENUM rating      |
         +------------------+

                        Figure 19: Confidence Class

   The element content expresses a numerical assessment in the
   confidence of the data when the value of the rating attribute is
   "numeric".  Otherwise, this element should be empty.

   The Confidence class has one attribute.

   rating
      Required.  ENUM.  A rating of the analytical validity of the
      specified Assessment.  The permitted values are shown below.
      There is no default value.

      1.  low.  Low confidence in the validity.

      2.  medium.  Medium confidence in the validity.

      3.  high.  High confidence in the validity.

      4.  numeric.  The element content contains a number that conveys
          the confidence of the data.  The semantics of this number
          outside the scope of this specification.

3.11.  History Class

   The History class is a log of the significant events or actions
   performed by the involved parties during the course of handling the
   incident.

   The level of detail maintained in this log is left up to the
   discretion of those handling the incident.

   +------------------+
   | History          |
   +------------------+
   | ENUM restriction |<>--{1..*}--[ HistoryItem ]
   |                  |
   +------------------+





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                       Figure 20: The History Class

   The class that constitutes History is:

   HistoryItem
      One or many.  Entry in the history log of significant events or
      actions performed by the involved parties.

   The History class has one attribute:

   restriction
      Optional.  ENUM.  This attribute is defined in Section 3.2.

3.11.1.  HistoryItem Class

   The HistoryItem class is an entry in the History (Section 3.11) log
   that documents a particular action or event that occurred in the
   course of handling the incident.  The details of the entry are a
   free-form description, but each can be categorized with the type
   attribute.

   +-------------------+
   | HistoryItem       |
   +-------------------+
   | ENUM restriction  |<>----------[ DateTime       ]
   | ENUM action       |<>--{0..1}--[ IncidentId     ]
   | STRING ext-action |<>--{0..1}--[ Contact        ]
   |                   |<>--{0..*}--[ Description    ]
   |                   |<>--{0..*}--[ AdditionalData ]
   +-------------------+

                       Figure 21: HistoryItem Class

   The aggregate classes that constitute HistoryItem are:

   DateTime
      One. Timestamp of this entry in the history log (e.g., when the
      action described in the Description was taken).

   IncidentID
      Zero or One. In a history log created by multiple parties, the
      IncidentID provides a mechanism to specify which CSIRT created a
      particular entry and references this organization's incident
      tracking number.  When a single organization is maintaining the
      log, this class can be ignored.






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   Contact
      Zero or One. Provides contact information for the person that
      performed the action documented in this class.

   Description
      Zero or many.  ML_STRING.  A free-form textual description of the
      action or event.

   AdditionalData
      Zero or many.  A mechanism by which to extend the data model.

   The HistoryItem class has three attributes:

   restriction
      Optional.  ENUM.  This attribute has been defined in Section 3.2.

   action
      Required.  ENUM.  Classifies a performed action or occurrence
      documented in this history log entry.  As activity will likely
      have been instigated either through a previously conveyed
      expectation or internal investigation, this attribute is identical
      to the category attribute of the Expectation class.  The
      difference is only one of tense.  When an action is in this class,
      it has been completed.  See Section 3.13.

   ext-action
      Optional.  STRING.  A means by which to extend the action
      attribute.  See Section 5.1.

3.12.  EventData Class

   The EventData class describes a particular event of the incident for
   a given set of hosts or networks.  This description includes the
   systems from which the activity originated and those targeted, an
   assessment of the techniques used by the intruder, the impact of the
   activity on the organization, and any forensic evidence discovered.















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   +------------------+
   | EventData        |
   +------------------+
   | ENUM restriction |<>--{0..*}--[ Description    ]
   |                  |<>--{0..1}--[ DetectTime     ]
   |                  |<>--{0..1}--[ StartTime      ]
   |                  |<>--{0..1}--[ EndTime        ]
   |                  |<>--{0..*}--[ Contact        ]
   |                  |<>--{0..1}--[ Assessment     ]
   |                  |<>--{0..*}--[ Method         ]
   |                  |<>--{0..*}--[ Flow           ]
   |                  |<>--{0..*}--[ Expectation    ]
   |                  |<>--{0..1}--[ Record         ]
   |                  |<>--{0..*}--[ EventData      ]
   |                  |<>--{0..*}--[ AdditionalData ]
   +------------------+

                      Figure 22: The EventData Class

   The aggregate classes that constitute EventData are:

   Description
      Zero or more.  ML_STRING.  A free-form textual description of the
      event.

   DetectTime
      Zero or one.  The time the event was detected.

   StartTime
      Zero or one.  The time the event started.

   EndTime
      Zero or one.  The time the event ended.

   Contact
      Zero or more.  Contact information for the parties involved in the
      event.

   Assessment
      Zero or one.  The impact of the event on the target and the
      actions taken.

   Method
      Zero or more.  The technique used by the intruder in the event.







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   Flow
      Zero or more.  A description of the systems or networks involved.

   Expectation
      Zero or more.  The expected action to be performed by the
      recipient for the described event.

   Record
      Zero or one.  Supportive data (e.g., log files) that provides
      additional information about the event.

   EventData
      Zero or more.  EventData instances contained within another
      EventData instance inherit the values of the parent(s); this
      recursive definition can be used to group common data pertaining
      to multiple events.  When EventData elements are defined
      recursively, only the leaf instances (those EventData instances
      not containing other EventData instances) represent actual events.

   AdditionalData
      Zero or more.  An extension mechanism for data not explicitly
      represented in the data model.

   At least one of the aggregate classes MUST be present in an instance
   of the EventData class.  This is not enforced in the IODEF schema as
   there is no simple way to accomplish it.

   The EventData class has one attribute:

   restriction
      Optional.  ENUM.  This attribute is defined in Section 3.2.

3.12.1.  Relating the Incident and EventData Classes

   There is substantial overlap in the Incident and EventData classes.
   Nevertheless, the semantics of these classes are quite different.
   The Incident class provides summary information about the entire
   incident, while the EventData class provides information about the
   individual events comprising the incident.  In the most common case,
   the EventData class will provide more specific information for the
   general description provided in the Incident class.  However, it may
   also be possible that the overall summarized information about the
   incident conflicts with some individual information in an EventData
   class when there is a substantial composition of various events in
   the incident.  In such a case, the interpretation of the more
   specific EventData MUST supersede the more generic information
   provided in IncidentData.




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3.12.2.  Cardinality of EventData

   The EventData class can be thought of as a container for the
   properties of an event in an incident.  These properties include: the
   hosts involved, impact of the incident activity on the hosts,
   forensic logs, etc.  With an instance of the EventData class, hosts
   (i.e., System class) are grouped around these common properties.

   The recursive definition (or instance property inheritance) of the
   EventData class (the EventData class is aggregated into the EventData
   class) provides a way to related information without requiring the
   explicit use of unique attribute identifiers in the classes or
   duplicating information.  Instead, the relative depth (nesting) of a
   class is used to group (relate) information.

   For example, an EventData class might be used to describe two
   machines involved in an incident.  This description can be achieved
   using multiple instances of the Flow class.  It happens that there is
   a common technical contact (i.e., Contact class) for these two
   machines, but the impact (i.e., Assessment class) on them is
   different.  A depiction of the representation for this situation can
   be found in Figure 23.

   +------------------+
   | EventData        |
   +------------------+
   |                  |<>----[ Contact    ]
   |                  |
   |                  |<>----[ EventData  ]<>----[ Flow     ]
   |                  |      [            ]<>----[ Assessment ]
   |                  |
   |                  |<>----[ EventData  ]<>----[ Flow     ]
   |                  |      [            ]<>----[ Assessment ]
   +------------------+

                Figure 23: Recursion in the EventData Class

3.13.  Expectation Class

   The Expectation class conveys to the recipient of the IODEF document
   the actions the sender is requesting.  The scope of the requested
   action is limited to purview of the EventData class in which this
   class is aggregated.








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   +-------------------+
   | Expectation       |
   +-------------------+
   | ENUM restriction  |<>--{0..*}--[ Description ]
   | ENUM severity     |<>--{0..1}--[ StartTime   ]
   | ENUM action       |<>--{0..1}--[ EndTime     ]
   | STRING ext-action |<>--{0..1}--[ Contact     ]
   +-------------------+

                     Figure 24: The Expectation Class

   The aggregate classes that constitute Expectation are:

   Description
      Zero or many.  ML_STRING.  A free-form description of the desired
      action(s).

   StartTime
      Zero or one.  The time at which the action should be performed.  A
      timestamp that is earlier than the ReportTime specified in the
      Incident class denotes that the expectation should be fulfilled as
      soon as possible.  The absence of this element leaves the
      execution of the expectation to the discretion of the recipient.

   EndTime
      Zero or one.  The time by which the action should be completed.
      If the action is not carried out by this time, it should no longer
      be performed.

   Contact
      Zero or one.  The expected actor for the action.

   The Expectations class has four attributes:

   restriction
      Optional.  ENUM.  This attribute is defined in Section 3.2.

   severity
      Optional.  ENUM.  Indicates the desired priority of the action.
      This attribute is an enumerated list with no default value, and
      the semantics of these relative measures are context dependent.

      1.  low.  Low priority

      2.  medium.  Medium priority

      3.  high.  High priority




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   action
      Optional.  ENUM.  Classifies the type of action requested.  This
      attribute is an enumerated list with no default value.

      1.   nothing.  No action is requested.  Do nothing with the
           information.

      2.   contact-source-site.  Contact the site(s) identified as the
           source of the activity.

      3.   contact-target-site.  Contact the site(s) identified as the
           target of the activity.

      4.   contact-sender.  Contact the originator of the document.

      5.   investigate.  Investigate the systems(s) listed in the event.

      6.   block-host.  Block traffic from the machine(s) listed as
           sources the event.

      7.   block-network.  Block traffic from the network(s) lists as
           sources in the event.

      8.   block-port.  Block the port listed as sources in the event.

      9.   rate-limit-host.  Rate-limit the traffic from the machine(s)
           listed as sources in the event.

      10.  rate-limit-network.  Rate-limit the traffic from the
           network(s) lists as sources in the event.

      11.  rate-limit-port.  Rate-limit the port(s) listed as sources in
           the event.

      12.  remediate-other.  Remediate the activity in a way other than
           by rate limiting or blocking.

      13.  status-triage.  Conveys receipts and the triaging of an
           incident.

      14.  status-new-info.  Conveys that new information was received
           for this incident.

      15.  other.  Perform some custom action described in the
           Description class.

      16.  ext-value.  An escape value used to extend this attribute.
           See Section 5.1.



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   ext-action
      Optional.  STRING.  A means by which to extend the action
      attribute.  See Section 5.1.

3.14.  Flow Class

   The Flow class groups related the source and target hosts.

   +------------------+
   | Flow             |
   +------------------+
   |                  |<>--{1..*}--[ System   ]
   +------------------+

                         Figure 25: The Flow Class

   The aggregate class that constitutes Flow is:

   System
      One or More.  A host or network involved in an event.

   The Flow System class has no attributes.

3.15.  System Class

   The System class describes a system or network involved in an event.
   The systems or networks represented by this class are categorized
   according to the role they played in the incident through the
   category attribute.  The value of this category attribute dictates
   the semantics of the aggregated classes in the System class.  If the
   category attribute has a value of "source", then the aggregated
   classes denote the machine and service from which the activity is
   originating.  With a category attribute value of "target" or
   "intermediary", then the machine or service is the one targeted in
   the activity.  A value of "sensor" dictates that this System was part
   of an instrumentation to monitor the network.















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   +---------------------+
   | System              |
   +---------------------+
   | ENUM restriction    |<>----------[ Node            ]
   | ENUM category       |<>--{0..*}--[ Service         ]
   | STRING ext-category |<>--{0..*}--[ OperatingSystem ]
   | STRING interface    |<>--{0..*}--[ Counter         ]
   | ENUM spoofed        |<>--{0..*}--[ Description     ]
   |                     |<>--{0..*}--[ AdditionalData  ]
   +---------------------+

                        Figure 26: The System Class

   The aggregate classes that constitute System are:

   Node
      One. A host or network involved in the incident.

   Service
      Zero or more.  A network service running on the system.

   OperatingSystem
      Zero or one.  The operating system running on the system.

   Counter
      Zero or more.  A counter with which to summarize properties of
      this host or network.

   Description
      Zero or more.  ML_STRING.  A free-form text description of the
      System.

   AdditionalData
      Zero or many.  A mechanism by which to extend the data model.

   The System class has five attributes:

   restriction
      Optional.  ENUM.  This attribute is defined in Section 3.2.

   category
      Required.  ENUM.  Classifies the role the host or network played
      in the incident.  The possible values are:

      1.  source.  The System was the source of the event.

      2.  target.  The System was the target of the event.




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      3.  intermediate.  The System was an intermediary in the event.

      4.  sensor.  The System was a sensor monitoring the event.

      5.  infrastructure.  The System was an infrastructure node of
          IODEF document exchange.

      6.  ext-value.  An escape value used to extend this attribute.
          See Section 5.1.

   ext-category
      Optional.  STRING.  A means by which to extend the category
      attribute.  See Section 5.1.

   interface
      Optional.  STRING.  Specifies the interface on which the event(s)
      on this System originated.  If the Node class specifies a network
      rather than a host, this attribute has no meaning.

   spoofed
      Optional.  ENUM.  An indication of confidence in whether this
      System was the true target or attacking host.  The permitted
      values for this attribute are shown below.  The default value is
      "unknown".

      1.  unknown.  The accuracy of the category attribute value is
          unknown.

      2.  yes.  The category attribute value is probably incorrect.  In
          the case of a source, the System is likely a decoy; with a
          target, the System was likely not the intended victim.

      3.  no.  The category attribute value is believed to be correct.

3.16.  Node Class

   The Node class names a system (e.g., PC, router) or network.

   This class was derived from the IDMEF [17].












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   +---------------+
   | Node          |
   +---------------+
   |               |<>--{0..*}--[ NodeName ]
   |               |<>--{0..*}--[ Address  ]
   |               |<>--{0..1}--[ Location ]
   |               |<>--{0..1}--[ DateTime ]
   |               |<>--{0..*}--[ NodeRole ]
   |               |<>--{0..*}--[ Counter  ]
   +---------------+

                         Figure 27: The Node Class

   The aggregate classes that constitute Node are:

   NodeName
      Zero or more.  ML_STRING.  The name of the Node (e.g., fully
      qualified domain name).  This information MUST be provided if no
      Address information is given.

   Address
      Zero or more.  The hardware, network, or application address of
      the Node.  If a NodeName is not provided, at least one Address
      MUST be specified.

   Location
      Zero or one.  ML_STRING.  A free-from description of the physical
      location of the equipment.

   DateTime
      Zero or one.  A timestamp of when the resolution between the name
      and address was performed.  This information SHOULD be provided if
      both an Address and NodeName are specified.

   NodeRole
      Zero or more.  The intended purpose of the Node.

   Counter
      Zero or more.  A counter with which to summarizes properties of
      this host or network.

3.16.1.  Counter Class

   The Counter class summarize multiple occurrences of some event, or
   conveys counts or rates on various features (e.g., packets, sessions,
   events).





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   The value of the counter is the element content with its units
   represented in the type attribute.  A rate for a given feature can be
   expressed by setting the duration attribute.  The complete semantics
   are entirely context dependent based on the class in which the
   Counter is aggregated.

   +---------------------+
   | Counter             |
   +---------------------+
   | REAL                |
   |                     |
   | ENUM type           |
   | STRING ext-type     |
   | STRING meaning      |
   | ENUM duration       |
   | STRING ext-duration |
   +---------------------+

                       Figure 28: The Counter Class

   The Counter class has three attribute:

   type
      Required.  ENUM.  Specifies the units of the element content.

      1.   byte.  Count of bytes.

      2.   packet.  Count of packets.

      3.   flow.  Count of flow (e.g., NetFlow records).

      4.   session.  Count of sessions.

      5.   alert.  Count of notifications generated by another system
           (e.g., IDS or SIM).

      6.   message.  Count of messages (e.g., mail messages).

      7.   event.  Count of events.

      8.   host.  Count of hosts.

      9.   site.  Count of site.

      10.  organization.  Count of organizations.






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      11.  ext-value.  An escape value used to extend this attribute.
           See Section 5.1.

   ext-type
      Optional.  STRING.  A means by which to extend the type attribute.
      See Section 5.1.

   duration
      Optional.  ENUM.  If present, the Counter class represents a rate
      rather than a count over the entire event.  In that case, this
      attribute specifies the denominator of the rate (where the type
      attribute specified the nominator).  The possible values of this
      attribute are defined in Section 3.10.2

   ext-duration
      Optional.  STRING.  A means by which to extend the duration
      attribute.  See Section 5.1.

3.16.2.  Address Class

   The Address class represents a hardware (layer-2), network (layer-3),
   or application (layer-7) address.

   This class was derived from the IDMEF [17].

   +---------------------+
   | Address             |
   +---------------------+
   | ENUM category       |
   | STRING ext-category |
   | STRING vlan-name    |
   | INTEGER vlan-num    |
   +---------------------+

                       Figure 29: The Address Class

   The Address class has four attributes:

   category
      Required.  ENUM.  The type of address represented.  The permitted
      values for this attribute are shown below.  The default value is
      "ipv4-addr".

      1.   asn.  Autonomous System Number

      2.   atm.  Asynchronous Transfer Mode (ATM) address





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      3.   e-mail.  Electronic mail address (RFC 822)

      4.   ipv4-addr.  IPv4 host address in dotted-decimal notation
           (a.b.c.d)

      5.   ipv4-net.  IPv4 network address in dotted-decimal notation,
           slash, significant bits (a.b.c.d/nn)

      6.   ipv4-net-mask.  IPv4 network address in dotted-decimal
           notation, slash, network mask in dotted-decimal notation
           (a.b.c.d/w.x.y.z)

      7.   ipv6-addr.  IPv6 host address

      8.   ipv6-net.  IPv6 network address, slash, significant bits

      9.   ipv6-net-mask.  IPv6 network address, slash, network mask

      10.  mac.  Media Access Control (MAC) address

      11.  ext-value.  An escape value used to extend this attribute.
           See Section 5.1.

   ext-category
      Optional.  STRING.  A means by which to extend the category
      attribute.  See Section 5.1.

   vlan-name
      Optional.  STRING.  The name of the Virtual LAN to which the
      address belongs.

   vlan-num
      Optional.  STRING.  The number of the Virtual LAN to which the
      address belongs.

3.16.3.  NodeRole Class

   The NodeRole class describes the intended function performed by a
   particular host.












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         +---------------------+
         | NodeRole            |
         +---------------------+
         | ENUM category       |
         | STRING ext-category |
         | ENUM lang           |
         +---------------------+

                       Figure 30: The NodeRole Class

   The NodeRole class has three attributes:

   category
      Required.  ENUM.  Functionality provided by a node.

      1.   client.  Client computer

      2.   server-internal.  Server with internal services

      3.   server-public.  Server with public services

      4.   www.  WWW server

      5.   mail.  Mail server

      6.   messaging.  Messaging server (e.g., NNTP, IRC, IM)

      7.   streaming.  Streaming-media server

      8.   voice.  Voice server (e.g., SIP, H.323)

      9.   file.  File server (e.g., SMB, CVS, AFS)

      10.  ftp.  FTP server

      11.  p2p.  Peer-to-peer node

      12.  name.  Name server (e.g., DNS, WINS)

      13.  directory.  Directory server (e.g., LDAP, finger, whois)

      14.  credential.  Credential server (e.g., domain controller,
           Kerberos)

      15.  print.  Print server

      16.  application.  Application server




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      17.  database.  Database server

      18.  infra.  Infrastructure server (e.g., router, firewall, DHCP)

      19.  log.  Logserver (e.g., syslog)

      20.  ext-value.  An escape value used to extend this attribute.
           See Section 5.1.

   ext-category
      Optional.  STRING.  A means by which to extend the category
      attribute.  See Section 5.1.

   lang
      Required.  ENUM.  A valid language code per RFC 4646 [7]
      constrained by the definition of "xs:language".  The
      interpretation of this code is described in Section 6.

3.17.  Service Class

   The Service class describes a network service of a host or network.
   The service is identified by specific port or list of ports, along
   with the application listening on that port.

   When Service occurs as an aggregate class of a System that is a
   source, then this service is the one from which activity of interest
   is originating.  Conversely, when Service occurs as an aggregate
   class of a System that is a target, then that service is the one to
   which activity of interest is directed.

   This class was derived from the IDMEF [17].

   +---------------------+
   | Service             |
   +---------------------+
   | INTEGER ip_protocol |<>--{0..1}--[ Port        ]
   |                     |<>--{0..1}--[ Portlist    ]
   |                     |<>--{0..1}--[ ProtoCode   ]
   |                     |<>--{0..1}--[ ProtoType   ]
   |                     |<>--{0..1}--[ ProtoFlags  ]
   |                     |<>--{0..1}--[ Application ]
   +---------------------+

                       Figure 31: The Service Class

   The aggregate classes that constitute Service are:





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   Port
      Zero or one.  INTEGER.  A port number.

   Portlist
      Zero or one.  PORTLIST.  A list of port numbers formatted
      according to Section 2.10.

   ProtoCode
      Zero or one.  INTEGER.  A layer-4 protocol-specific code field
      (e.g., ICMP code field).

   ProtoType
      Zero or one.  INTEGER.  A layer-4 protocol specific type field
      (e.g., ICMP type field).

   ProtoFlags
      Zero or one.  INTEGER.  A layer-4 protocol specific flag field
      (e.g., TCP flag field).

   Application
      Zero or more.  The application bound to the specified Port or
      Portlist.

   Either a Port or Portlist class MUST be specified for a given
   instance of a Service class.

   For a given source, System@type="source", a corresponding target,
   System@type="target", maybe defined, or vice versa.  When a Portlist
   class is defined in the Service class of both the source and target
   in a given instance of the Flow class, there MUST be symmetry in the
   enumeration of the ports.  Thus, if n-ports are listed for a source,
   n-ports should be listed for the target.  Likewise, the ports should
   be listed in an identical sequence such that the n-th port in the
   source corresponds to the n-th port of the target.  This symmetry in
   listing and sequencing of ports applies whether there are 1-to-1,
   1-to-many, or many-to-many sources-to-targets.  In the 1-to-many or
   many-to-many, the exact order in which the System classes are
   enumerated in the Flow class is significant.

   The Service class has one attribute:

   ip_protocol
      Required.  INTEGER.  The IANA protocol number.








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3.17.1.  Application Class

   The Application class describes an application running on a System
   providing a Service.

   +--------------------+
   | Application        |
   +--------------------+
   | STRING swid        |<>--{0..1}--[ URL        ]
   | STRING configid    |
   | STRING vendor      |
   | STRING family      |
   | STRING name        |
   | STRING version     |
   | STRING patch       |
   +--------------------+

                     Figure 32: The Application Class

   The aggregate class that constitutes Application is:

   URL
      Zero or one.  URL.  A URL describing the application.

   The Application class has seven attributes:

   swid
      Optional.  STRING.  An identifier that can be used to reference
      this software.

   configid
      Optional.  STRING.  An identifier that can be used to reference a
      particular configuration of this software.

   vendor
      Optional.  STRING.  Vendor name of the software.

   family
      Optional.  STRING.  Family of the software.

   name
      Optional.  STRING.  Name of the software.

   version
      Optional.  STRING.  Version of the software.






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   patch
      Optional.  STRING.  Patch or service pack level of the software.

3.18.  OperatingSystem Class

   The OperatingSystem class describes the operating system running on a
   System.  The definition is identical to the Application class
   (Section 3.17.1).

3.19.  Record Class

   The Record class is a container class for log and audit data that
   provides supportive information about the incident.  The source of
   this data will often be the output of monitoring tools.  These logs
   should substantiate the activity described in the document.

   +------------------+
   | Record           |
   +------------------+
   | ENUM restriction |<>--{1..*}--[ RecordData ]
   +------------------+

                          Figure 33: Record Class

   The aggregate class that constitutes Record is:

   RecordData
      One or more.  Log or audit data generated by a particular type of
      sensor.  Separate instances of the RecordData class SHOULD be used
      for each sensor type.

   The Record class has one attribute:

   restriction
      Optional.  ENUM.  This attribute has been defined in Section 3.2.

3.19.1.  RecordData Class

   The RecordData class groups log or audit data from a given sensor
   (e.g., IDS, firewall log) and provides a way to annotate the output.











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   +------------------+
   | RecordData       |
   +------------------+
   | ENUM restriction |<>--{0..1}--[ DateTime        ]
   |                  |<>--{0..*}--[ Description     ]
   |                  |<>--{0..1}--[ Application     ]
   |                  |<>--{0..*}--[ RecordPattern   ]
   |                  |<>--{1..*}--[ RecordItem      ]
   |                  |<>--{0..*}--[ AdditionalData  ]
   +------------------+

                      Figure 34: The RecordData Class

   The aggregate classes that constitutes RecordData is:

   DateTime
      Zero or one.  Timestamp of the RecordItem data.

   Description
      Zero or more.  ML_STRING.  Free-form textual description of the
      provided RecordItem data.  At minimum, this description should
      convey the significance of the provided RecordItem data.

   Application
      Zero or one.  Information about the sensor used to generate the
      RecordItem data.

   RecordPattern
      Zero or more.  A search string to precisely find the relevant data
      in a RecordItem.

   RecordItem
      One or more.  Log, audit, or forensic data.

   AdditionalData
      Zero or one.  An extension mechanism for data not explicitly
      represented in the data model.

   The RecordData class has one attribute:

   restriction
      Optional.  ENUM.  This attribute has been defined in Section 3.2.









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3.19.2.  RecordPattern Class

   The RecordPattern class describes where in the content of the
   RecordItem relevant information can be found.  It provides a way to
   reference subsets of information, identified by a pattern, in a large
   log file, audit trail, or forensic data.

   +-----------------------+
   | RecordPattern         |
   +-----------------------+
   | STRING                |
   |                       |
   | ENUM type             |
   | STRING ext-type       |
   | INTEGER offset        |
   | ENUM offsetunit       |
   | STRING ext-offsetunit |
   | INTEGER instance      |
   +-----------------------+

                    Figure 35: The RecordPattern Class

   The specific pattern to search with in the RecordItem is defined in
   the body of the element.  It is further annotated by four attributes:

   type
      Required.  ENUM.  Describes the type of pattern being specified in
      the element content.  The default is "regex".

      1.  regex. regular expression, per Appendix F of [3].

      2.  binary.  Binhex encoded binary pattern, per the HEXBIN data
          type.

      3.  xpath.  XML Path (XPath) [5]

      4.  ext-value.  An escape value used to extend this attribute.
          See Section 5.1.

   ext-type
      Optional.  STRING.  A means by which to extend the type attribute.
      See Section 5.1.

   offset
      Optional.  INTEGER.  Amount of units (determined by the offsetunit
      attribute) to seek into the RecordItem data before matching the
      pattern.




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   offsetunit
      Optional.  ENUM.  Describes the units of the offset attribute.
      The default is "line".

      1.  line.  Offset is a count of lines.

      2.  binary.  Offset is a count of bytes.

      3.  ext-value.  An escape value used to extend this attribute.
          See Section 5.1.

   ext-offsetunit
      Optional.  STRING.  A means by which to extend the offsetunit
      attribute.  See Section 5.1.

   instance
      Optional.  INTEGER.  Number of types to apply the specified
      pattern.

3.19.3.  RecordItem Class

   The RecordItem class provides a way to incorporate relevant logs,
   audit trails, or forensic data to support the conclusions made during
   the course of analyzing the incident.  The class supports both the
   direct encapsulation of the data, as well as, provides primitives to
   reference data stored elsewhere.

   This class is identical to AdditionalData class (Section 3.6).

4.  Processing Considerations

   This section defines additional requirements on creating and parsing
   IODEF documents.

4.1.  Encoding

   Every IODEF document MUST begin with an XML declaration, and MUST
   specify the XML version used.  If UTF-8 encoding is not used, the
   character encoding MUST also be explicitly specified.  The IODEF
   conforms to all XML data encoding conventions and constraints.

   The XML declaration with no character encoding will read as follows:

   <?xml version="1.0" ?>

   When a character encoding is specified, the XML declaration will read
   like the following:




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   <?xml version="1.0" encoding="charset" ?>

   Where "charset" is the name of the character encoding as registered
   with the Internet Assigned Numbers Authority (IANA), see [9].

   The following characters have special meaning in XML and MUST be
   escaped with their entity reference equivalent: "&", "<", ">", "\""
   (double quotation mark), and "'" (apostrophe).  These entity
   references are "&amp;", "&lt;", "&gt;", "&quot;", and "&apos;"
   respectively.

4.2.  IODEF Namespace

   The IODEF schema declares a namespace of
   "urn:ietf:params:xml:ns:iodef-1.0" and registers it per [4].  Each
   IODEF document SHOULD include a valid reference to the IODEF schema
   using the "xsi:schemaLocation" attribute.  An example of such a
   declaration would look as follows:

   <IODEF-Document
      version="1.00" lang="en-US"
      xmlns:iodef="urn:ietf:params:xml:ns:iodef-1.0"
      xsi:schemaLocation="urn:ietf:params:xmls:schema:iodef-1.0">

4.3.  Validation

   The IODEF documents MUST be well-formed XML and SHOULD be validated
   against the schema described in Section 8.  However, mere conformance
   to the schema is not sufficient for a semantically valid IODEF
   document.  There is additional specification in the text of Section 3
   that cannot be readily encoded in the schema and it must also be
   considered by an IODEF parser.  The following is a list of
   discrepancies in what is more strictly specified in the normative
   text (Section 3), but not enforced in the IODEF schema:

   o  The elements or attributes that are defined as POSTAL, NAME,
      PHONE, and EMAIL data-types are implemented as "xs:string", but
      more rigid formatting requirements are specified in the text.

   o  The IODEF-Document@lang and MLStringType@lang attributes are
      declared as an "xs:language" that constrains values with a regular
      expression.  However, the value of this attribute still needs to
      be validated against the list of possible enumerated values is
      defined in [7].

   o  The MonetaryImpact@currency attribute is declared as an "xs:
      string", but the list of valid values as defined in [14].




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   o  All of the aggregated classes Contact and EventData are optional
      in the schema, but at least one of these aggregated classes MUST
      be present.

   o  There are multiple conventions that can be used to categorize a
      system using the NodeRole class or to specify software with the
      Application and OperatingSystem classes.  IODEF parsers MUST
      accept incident reports that do not use these fields in accordance
      with local conventions.

   o  The Confidence@rating attribute determines whether the element
      content of Confidence should be empty.

   o  The Address@type attribute determines the format of the element
      content.

   o  The attributes AdditionalData@dtype and RecordItem@dtype derived
      from iodef:ExtensionType determine the semantics and formatting of
      the element content.

   o  Symmetry in the enumerated ports of a Portlist class is required
      between sources and targets.  See Section 3.17.

5.  Extending the IODEF

   In order to support the changing activity of CSIRTS, the IODEF data
   model will need to evolve along with them.  This section discusses
   how new data elements that have no current representation in the data
   model can be incorporated into the IODEF.  These techniques are
   designed so that adding new data will not require a change to the
   IODEF schema.  With proven value, well documented extensions can be
   incorporated into future versions of the specification.  However,
   this approach also supports private extensions relevant only to a
   closed consortium.

5.1.  Extending the Enumerated Values of Attributes

   The data model supports a means by which to add new enumerated values
   to an attribute.  For each attribute that supports this extension
   technique, there is a corresponding attribute in the same element
   whose name is identical, less a prefix of "ext-".  This special
   attribute is referred to as the extension attribute, and the
   attribute being extended is referred to as an extensible attribute.
   For example, an extensible attribute named "foo" will have a
   corresponding extension attribute named "ext-foo".  An element may
   have many extensible, and therefore many extension, attributes.





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   In addition to a corresponding extension attribute, each extensible
   attribute has "ext-value" as one its possible values.  This
   particular value serves as an escape sequence and has no valid
   meaning.

   In order to add a new enumerated value to an extensible attribute,
   the value of this attribute MUST be set to "ext-value", and the new
   desired value MUST be set in the corresponding extension attribute.
   For example, an extended instance of the type attribute of the Impact
   class would look as follows:

    <Impact type="ext-value" ext-type="new-attack-type">

   A given extension attribute MUST NOT be set unless the corresponding
   extensible attribute has been set to "ext-value".

5.2.  Extending Classes

   The classes of the data model can be extended only through the use of
   the AdditionalData and RecordItem classes.  These container classes,
   collectively referred to as the extensible classes, are implemented
   with the iodef:ExtensionType data type in the schema.  They provide
   the ability to have new atomic or XML-encoded data elements in all of
   the top-level classes of the Incident class and a few of the more
   complicated subordinate classes.  As there are multiple instances of
   the extensible classes in the data model, there is discretion on
   where to add a new data element.  It is RECOMMENDED that the
   extension be placed in the most closely related class to the new
   information.

   Extensions using the atomic data types (i.e., all values of the dtype
   attributes other than "xml") MUST:

   1.  Set the element content of extensible class to the desired value,
       and

   2.  Set the dtype attribute to correspond to the data type of the
       element content.

   The following guidelines exist for extensions using XML:

   1.  The element content of the extensible class MUST be set to the
       desired value and the dtype attribute MUST be set to "xml".

   2.  The extension schema MUST declare a separate namespace.  It is
       RECOMMENDED that these extensions have the prefix "iodef-".





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   3.  It is RECOMMENDED that extension schemas follow the naming
       convention of the IODEF data model.  The names of all elements
       are capitalized.  For composed names, a capital letter is used
       for each word.  Attribute names are lower case.

   4.  When a parser encounters an IODEF document with an extension it
       does not understand, this extension MUST be ignored (and not
       processed), but the remainder of the document MUST be processed.
       Parsers will be able to identify these extensions for which they
       have no processing logic through the namespace declaration.
       Parsers that encounter an unrecognized element in a namespace
       that they do support SHOULD reject the document as a syntax
       error.

   5.  Implementations SHOULD NOT download schemas at runtime due to the
       security implications, and extensions MUST NOT be required to
       provide a resolvable location of their schema.

   The following schema and XML document excerpt provide a template for
   an extension schema and its use in the IODEF document.

   This example schema defines a namespace of "iodef-extension1" and a
   single element named "newdata".

     <xs:schema
        targetNamespace="iodef-extension1.xsd"
        xmlns:iodef-extension1="iodef-extension1.xsd"
        xmlns:xs="http://www.w3.org/2001/XMLSchema">
        attributeFormDefault="unqualified"
        elementFormDefault="qualified">
      <xs:import
           namespace="urn:ietf:params:xml:ns:iodef-1.0"
           schemaLocation=" urn:ietf:params:xml:schema:iodef-1.0"/>

        <xs:element name="newdata" type="xs:string" />
     </xs:schema>

   The following XML excerpt demonstrates the use of the above schema as
   an extension to the IODEF.












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      <IODEF-Document
           version="1.00" lang="en-US"
           xmlns="urn:ietf:params:xml:ns:iodef-1.0"
           xmlns:iodef=" urn:ietf:params:xml:ns:iodef-1.0"
           xmlns:iodef-extension1="iodef-extension1.xsd"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="iodef-extension1.xsd">
          <Incident purpose="reporting">
          ...
          <AdditionalData dtype="xml" meaning="xml">
            <iodef-extension1:newdata>
               Field that could not be represented elsewhere
            </iodef-extension1:newdata>
          </AdditionalData>
          </Incident>
      </IODEF-Document>

6.  Internationalization Issues

   Internationalization and localization is of specific concern to the
   IODEF, since it is only through collaboration, often across language
   barriers, that certain incidents be resolved.  The IODEF supports
   this goal by depending on XML constructs, and through explicit design
   choices in the data model.

   Since IODEF is implemented as an XML Schema, it implicitly supports
   all the different character encodings, such as UTF-8 and UTF-16,
   possible with XML.  Additionally, each IODEF document MUST specify
   the language in which their contents are encoded.  The language can
   be specified with the attribute "xml:lang" (per Section 2.12 of [1])
   in the top-level element (i.e., IODEF-Document@lang) and letting all
   other elements inherit that definition.  All IODEF classes with a
   free-form text definition (i.e., all those defined of type iodef:
   MLStringType) can also specify a language different from the rest of
   the document.  The valid language codes for the "xml:lang" attribute
   are described in RFC 4646 [7].

   The data model supports multiple translations of free-form text.  In
   the places where free-text is used for descriptive purposes, the
   given class always has a one-to-many cardinality to its parent (e.g.,
   Description class).  The intent is to allow the identical text to be
   encoded in different instances of the same class, but each being in a
   different language.  This approach allows an IODEF document author to
   send recipients speaking different languages an identical document.
   The IODEF parser SHOULD extract the appropriate language relevant to
   the recipient.





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   While the intent of the data model is to provide internationalization
   and localization, the intent is not to do so at the detriment of
   interoperability.  While the IODEF does support different languages,
   the data model also relies heavily on standardized enumerated
   attributes that can crudely approximate the contents of the document.
   With this approach, a CSIRT should be able to make some sense of an
   IODEF document it receives even if the text based data elements are
   written in a language unfamiliar to the analyst.

7.  Examples

   This section provides examples of an incident encoded in the IODEF.
   These examples do not necessarily represent the only way to encode a
   particular incident.

7.1.  Worm

   An example of a CSIRT reporting an instance of the Code Red worm.

<?xml version="1.0" encoding="UTF-8"?>
<!-- This example demonstrates a report for a very
     old worm (Code Red) -->
<IODEF-Document version="1.00" lang="en"
  xmlns="urn:ietf:params:xml:ns:iodef-1.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="urn:ietf:params:xml:schema:iodef-1.0">
  <Incident purpose="reporting">
    <IncidentID name="csirt.example.com">189493</IncidentID>
    <ReportTime>2001-09-13T23:19:24+00:00</ReportTime>
    <Description>Host sending out Code Red probes</Description>
    <!-- An administrative privilege was attempted, but failed -->
    <Assessment>
      <Impact completion="failed" type="admin"/>
    </Assessment>
    <Contact role="creator" type="organization">
      <ContactName>Example.com CSIRT</ContactName>
      <RegistryHandle registry="arin">example-com</RegistryHandle>
      <Email>contact@csirt.example.com</Email>
    </Contact>
    <EventData>
      <Flow>
        <System category="source">
          <Node>
            <Address category="ipv4-addr">192.0.2.200</Address>
            <Counter type="event">57</Counter>
          </Node>
        </System>
        <System category="target">



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          <Node>
            <Address category="ipv4-net">192.0.2.16/28</Address>
          </Node>
          <Service ip_protocol="6">
            <Port>80</Port>
          </Service>
        </System>
      </Flow>
      <Expectation action="block-host" />
      <!-- <RecordItem> has an excerpt from a log -->
      <Record>
        <RecordData>
          <DateTime>2001-09-13T18:11:21+02:00</DateTime>
          <Description>Web-server logs</Description>
          <RecordItem dtype="string">
          192.0.2.1 - - [13/Sep/2001:18:11:21 +0200] "GET /default.ida?
          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
          </RecordItem>
            <!-- Additional logs -->
          <RecordItem dtype="url">
             http://mylogs.example.com/logs/httpd_access</RecordItem>
        </RecordData>
      </Record>
    </EventData>
    <History>
      <!-- Contact was previously made with the source network owner -->
      <HistoryItem action="contact-source-site">
        <DateTime>2001-09-14T08:19:01+00:00</DateTime>
        <Description>Notification sent to
                     constituency-contact@192.0.2.200</Description>
      </HistoryItem>
    </History>
  </Incident>
</IODEF-Document>

7.2.  Reconnaissance

   An example of a CSIRT reporting a scanning activity.

   <?xml version="1.0" encoding="UTF-8" ?>
   <!-- This example describes reconnaissance activity: one-to-one and
        one-to-many scanning -->






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   <IODEF-Document version="1.00" lang="en"
     xmlns="urn:ietf:params:xml:ns:iodef-1.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="urn:ietf:params:xml:schema:iodef-1.0">
     <Incident purpose="reporting">
       <IncidentID name="csirt.example.com">59334</IncidentID>
       <ReportTime>2006-08-02T05:54:02-05:00</ReportTime>
       <Assessment>
         <Impact type="recon" completion="succeeded" />
       </Assessment>
       <Method>
         <!-- Reference to the scanning tool "nmap" -->
         <Reference>
           <ReferenceName>nmap</ReferenceName>
           <URL>http://nmap.toolsite.example.com</URL>
         </Reference>
       </Method>
       <!-- Organizational contact and that for staff in that
            organization -->
       <Contact role="creator" type="organization">
         <ContactName>CSIRT for example.com</ContactName>
         <Email>contact@csirt.example.com</Email>
         <Telephone>+1 412 555 12345</Telephone>
         <!-- Since this <Contact> is nested, Joe Smith is part of the
             CSIRT for example.com -->
         <Contact role="tech" type="person" restriction="need-to-know">
           <ContactName>Joe Smith</ContactName>
           <Email>smith@csirt.example.com</Email>
         </Contact>
       </Contact>
       <EventData>
         <!-- Scanning activity as follows:
           192.0.2.1:60524 >> 192.0.2.3:137
                  192.0.2.1:60526 >> 192.0.2.3:138
                  192.0.2.1:60527 >> 192.0.2.3:139
                  192.0.2.1:60531 >> 192.0.2.3:445
         -->
         <Flow>
           <System category="source">
             <Node>
               <Address category="ipv4-addr">192.0.2.200</Address>
             </Node>
             <Service ip_protocol="6">
               <Portlist>60524,60526,60527,60531</Portlist>
             </Service>
           </System>
           <System category="target">
             <Node>



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               <Address category="ipv4-addr">192.0.2.201</Address>
             </Node>
             <Service ip_protocol="6">
               <Portlist>137-139,445</Portlist>
             </Service>
           </System>
         </Flow>
         <!-- Scanning activity as follows:
               192.0.2.2 >> 192.0.2.3/28:445 -->
         <Flow>
           <System category="source">
             <Node>
               <Address category="ipv4-addr">192.0.2.240</Address>
             </Node>
           </System>
           <System category="target">
             <Node>
               <Address category="ipv4-net">192.0.2.64/28</Address>
             </Node>
             <Service ip_protocol="6">
               <Port>445</Port>
             </Service>
           </System>
         </Flow>
       </EventData>
     </Incident>
   </IODEF-Document>

7.3.  Bot-Net Reporting

   An example of a CSIRT reporting a bot-network.

 <?xml version="1.0" encoding="UTF-8" ?>
 <!-- This example describes a compromise and subsequent installation
      of bots -->
 <IODEF-Document version="1.00" lang="en"
   xmlns="urn:ietf:params:xml:ns:iodef-1.0"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="urn:ietf:params:xml:schema:iodef-1.0">
   <Incident purpose="mitigation">
     <IncidentID name="csirt.example.com">908711</IncidentID>
     <ReportTime>2006-06-08T05:44:53-05:00</ReportTime>
     <Description>Large bot-net</Description>
     <Assessment>
       <Impact type="dos" severity="high" completion="succeeded" />






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     </Assessment>
     <Method>
       <!-- References a given piece of malware, "GT Bot" -->
       <Reference>
         <ReferenceName>GT Bot</ReferenceName>
       </Reference>
       <!-- References the vulnerability used to compromise the
            machines -->
       <Reference>
         <ReferenceName>CA-2003-22</ReferenceName>
         <URL>http://www.cert.org/advisories/CA-2003-22.html</URL>
         <Description>Root compromise via this IE vulnerability to
                      install the GT Bot</Description>
       </Reference>
     </Method>
     <!-- A member of the CSIRT that is coordinating this
          incident -->
     <Contact type="person" role="irt">
       <ContactName>Joe Smith</ContactName>
       <Email>jsmith@csirt.example.com</Email>
     </Contact>
     <EventData>
       <Description>These hosts are compromised and acting as bots
                    communicating with irc.example.com.</Description>
       <Flow>
         <!-- bot running on 192.0.2.1 and sending DoS traffic at
              10,000 bytes/second -->
         <System category="source">
           <Node>
             <Address category="ipv4-addr">192.0.2.1</Address>
           </Node>
           <Counter type="byte" duration="second">10000</Counter>
           <Description>bot</Description>
         </System>
         <!-- a second bot on 192.0.2.3 -->
         <System category="source">
           <Node>
             <Address category="ipv4-addr">192.0.2.3</Address>
           </Node>
           <Counter type="byte" duration="second">250000</Counter>
           <Description>bot</Description>
         </System>
         <!-- Command-and-control IRC server for these bots-->
         <System category="intermediate">
           <Node>
             <NodeName>irc.example.com</NodeName>
             <Address category="ipv4-addr">192.0.2.20</Address>
             <DateTime>2006-06-08T01:01:03-05:00</DateTime>



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           </Node>
           <Description>IRC server on #give-me-cmd channel</Description>
         </System>
       </Flow>
       <!-- Request to take these machines offline -->
       <Expectation action="investigate">
         <Description>Confirm the source and take machines off-line and
                      remediate</Description>
       </Expectation>
     </EventData>
   </Incident>
 </IODEF-Document>

7.4.  Watch List

   An example of a CSIRT conveying a watch-list.

<?xml version="1.0" encoding="UTF-8" ?>
<!-- This example demonstrates a trivial IP watch-list -->
<!-- @formatid is set to "watch-list-043" to demonstrate how additional
     semantics about this document could be conveyed assuming both
     parties understood it-->
<IODEF-Document version="1.00" lang="en" formatid="watch-list-043"
  xmlns="urn:ietf:params:xml:ns:iodef-1.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="urn:ietf:params:xml:schema:iodef-1.0">
  <Incident purpose="reporting" restriction="private">
    <IncidentID name="csirt.example.com">908711</IncidentID>
    <ReportTime>2006-08-01T00:00:00-05:00</ReportTime>
    <Description>Watch-list of known bad IPs or networks</Description>
    <Assessment>
      <Impact type="admin" completion="succeeded" />
      <Impact type="recon" completion="succeeded" />
    </Assessment>
    <Contact type="organization" role="creator">
      <ContactName>CSIRT for example.com</ContactName>
      <Email>contact@csirt.example.com</Email>
    </Contact>
    <!-- Separate <EventData> used to convey different <Expectation> -->
    <EventData>
      <Flow>
        <System category="source">
          <Node>
            <Address category="ipv4-addr">192.0.2.53</Address>
          </Node>






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          <Description>Source of numerous attacks</Description>
        </System>
      </Flow>
      <!-- Expectation class indicating that sender of list would like
           to be notified if activity from the host is seen -->
      <Expectation action="contact-sender" />
    </EventData>
    <EventData>
      <Flow>
        <System category="source">
          <Node>
            <Address category="ipv4-net">192.0.2.16/28</Address>
          </Node>
          <Description>
            Source of heavy scanning over past 1-month
          </Description>
        </System>
      </Flow>
      <Flow>
        <System category="source">
          <Node>
            <Address category="ipv4-addr">192.0.2.241</Address>
          </Node>
          <Description>C2 IRC server</Description>
        </System>
      </Flow>
      <!-- Expectation class recommends that these networks
           be filtered -->
      <Expectation action="block-host" />
    </EventData>
  </Incident>
</IODEF-Document>

8.  The IODEF Schema

  <?xml version="1.0" encoding="UTF-8"?>
  <xs:schema targetNamespace="urn:ietf:params:xml:ns:iodef-1.0"
             xmlns="urn:ietf:params:xml:ns:iodef-1.0"
             xmlns:iodef="urn:ietf:params:xml:ns:iodef-1.0"
             xmlns:xs="http://www.w3.org/2001/XMLSchema"
             elementFormDefault="qualified"
             attributeFormDefault="unqualified">

    <xs:annotation>
      <xs:documentation>
      Incident Object Description Exchange Format v1.00, see RFC 5070





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      </xs:documentation>
    </xs:annotation>

  <!--
   ====================================================================
   == IODEF-Document class                                           ==
   ====================================================================
  -->
    <xs:element name="IODEF-Document">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:Incident"
                      maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="version"
                      type="xs:string" fixed="1.00"/>
        <xs:attribute name="lang"
                      type="xs:language" use="required"/>
        <xs:attribute name="formatid"
                      type="xs:string"/>
      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   ===  Incident class                                              ===
   ====================================================================
  -->
    <xs:element name="Incident">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:IncidentID"/>
          <xs:element ref="iodef:AlternativeID"
                      minOccurs="0"/>
          <xs:element ref="iodef:RelatedActivity"
                      minOccurs="0"/>
          <xs:element ref="iodef:DetectTime"
                      minOccurs="0"/>
          <xs:element ref="iodef:StartTime"
                      minOccurs="0"/>
          <xs:element ref="iodef:EndTime"
                      minOccurs="0"/>
          <xs:element ref="iodef:ReportTime"/>
          <xs:element ref="iodef:Description"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Assessment"
                      maxOccurs="unbounded"/>
          <xs:element ref="iodef:Method"
                      minOccurs="0" maxOccurs="unbounded"/>



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          <xs:element ref="iodef:Contact"
                      maxOccurs="unbounded"/>
          <xs:element ref="iodef:EventData"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:History"
                      minOccurs="0"/>
          <xs:element ref="iodef:AdditionalData"
                      minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="purpose" use="required">
          <xs:simpleType>
            <xs:restriction base="xs:NMTOKEN">
              <xs:enumeration value="traceback"/>
              <xs:enumeration value="mitigation"/>
              <xs:enumeration value="reporting"/>
              <xs:enumeration value="other"/>
              <xs:enumeration value="ext-value"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
        <xs:attribute name="ext-purpose"
                      type="xs:string" use="optional"/>
        <xs:attribute name="lang"
                      type="xs:language"/>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type" default="private"/>
      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   ==  IncidentID class                                              ==
   ====================================================================
  -->
    <xs:element name="IncidentID" type="iodef:IncidentIDType"/>
    <xs:complexType name="IncidentIDType">
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="name"
                        type="xs:string" use="required"/>
          <xs:attribute name="instance"
                        type="xs:string" use="optional"/>
          <xs:attribute name="restriction"
                        type="iodef:restriction-type" default="public"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>





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  <!--
   ====================================================================
   ==  AlternativeID class                                           ==
   ====================================================================
  -->
    <xs:element name="AlternativeID">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:IncidentID"
                      maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type"/>
      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   ==  RelatedActivity class                                         ==
   ====================================================================
  -->
    <xs:element name="RelatedActivity">
      <xs:complexType>
        <xs:choice>
          <xs:element ref="iodef:IncidentID"
                      maxOccurs="unbounded"/>
          <xs:element ref="iodef:URL"
                      maxOccurs="unbounded"/>
        </xs:choice>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type"/>
      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   ===  AdditionalData class                                        ===
   ====================================================================
  -->
    <xs:element name="AdditionalData" type="iodef:ExtensionType"/>
  <!--
  ====================================================================
  ===  Contact class                                               ===
  ====================================================================
  -->
    <xs:element name="Contact">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:ContactName"
                      minOccurs="0"/>



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          <xs:element ref="iodef:Description"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:RegistryHandle"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:PostalAddress"
                      minOccurs="0"/>
          <xs:element ref="iodef:Email"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Telephone"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Fax"
                      minOccurs="0"/>
          <xs:element ref="iodef:Timezone"
                      minOccurs="0"/>
          <xs:element ref="iodef:Contact"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:AdditionalData"
                      minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="role" use="required">
          <xs:simpleType>
            <xs:restriction base="xs:NMTOKEN">
              <xs:enumeration value="creator"/>
              <xs:enumeration value="admin"/>
              <xs:enumeration value="tech"/>
              <xs:enumeration value="irt"/>
              <xs:enumeration value="cc"/>
              <xs:enumeration value="ext-value"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
        <xs:attribute name="ext-role"
                      type="xs:string" use="optional"/>
        <xs:attribute name="type" use="required">
          <xs:simpleType>
            <xs:restriction base="xs:NMTOKEN">
              <xs:enumeration value="person"/>
              <xs:enumeration value="organization"/>
              <xs:enumeration value="ext-value"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
        <xs:attribute name="ext-type"
                      type="xs:string" use="optional"/>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type"/>
      </xs:complexType>
    </xs:element>



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    <xs:element name="ContactName"
                type="iodef:MLStringType"/>
    <xs:element name="RegistryHandle">
      <xs:complexType>
        <xs:simpleContent>
          <xs:extension base="xs:string">
            <xs:attribute name="registry">
              <xs:simpleType>
                <xs:restriction base="xs:NMTOKEN">
                  <xs:enumeration value="internic"/>
                  <xs:enumeration value="apnic"/>
                  <xs:enumeration value="arin"/>
                  <xs:enumeration value="lacnic"/>
                  <xs:enumeration value="ripe"/>
                  <xs:enumeration value="afrinic"/>
                  <xs:enumeration value="local"/>
                  <xs:enumeration value="ext-value"/>
                </xs:restriction>
              </xs:simpleType>
            </xs:attribute>
            <xs:attribute name="ext-registry"
                          type="xs:string" use="optional"/>
          </xs:extension>
        </xs:simpleContent>
      </xs:complexType>
    </xs:element>

    <xs:element name="PostalAddress">
      <xs:complexType>
        <xs:simpleContent>
          <xs:extension base="iodef:MLStringType">
            <xs:attribute name="meaning"
                          type="xs:string" use="optional"/>
          </xs:extension>
        </xs:simpleContent>
      </xs:complexType>
    </xs:element>
    <xs:element name="Email" type="iodef:ContactMeansType"/>
    <xs:element name="Telephone" type="iodef:ContactMeansType"/>
    <xs:element name="Fax" type="iodef:ContactMeansType"/>

    <xs:complexType name="ContactMeansType">
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="meaning"
                        type="xs:string" use="optional"/>
        </xs:extension>
      </xs:simpleContent>



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    </xs:complexType>

  <!--
   ====================================================================
   ===  Time-based classes                                          ===
   ====================================================================
  -->
    <xs:element name="DateTime"
                type="xs:dateTime"/>
    <xs:element name="ReportTime"
                type="xs:dateTime"/>
    <xs:element name="DetectTime"
                type="xs:dateTime"/>
    <xs:element name="StartTime"
                type="xs:dateTime"/>
    <xs:element name="EndTime"
                type="xs:dateTime"/>
    <xs:element name="Timezone"
                type="iodef:TimezoneType"/>
    <xs:simpleType name="TimezoneType">
      <xs:restriction base="xs:string">
        <xs:pattern value="Z|[\+\-](0[0-9]|1[0-4]):[0-5][0-9]"/>
      </xs:restriction>
    </xs:simpleType>
  <!--
   ====================================================================
   ===  History class                                               ===
   ====================================================================
  -->
    <xs:element name="History">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:HistoryItem"
                      maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type" default="default"/>
      </xs:complexType>
    </xs:element>
    <xs:element name="HistoryItem">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:DateTime"/>
          <xs:element ref="iodef:IncidentID"
                      minOccurs="0"/>
          <xs:element ref="iodef:Contact"
                      minOccurs="0"/>
          <xs:element ref="iodef:Description"



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                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:AdditionalData"
                      minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type"/>
        <xs:attribute name="action"
                      type="iodef:action-type" use="required"/>
        <xs:attribute name="ext-action"
                      type="xs:string" use="optional"/>
      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   ===  Expectation class                                           ===
   ====================================================================
  -->
    <xs:element name="Expectation">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:Description"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:StartTime"
                      minOccurs="0"/>
          <xs:element ref="iodef:EndTime"
                      minOccurs="0"/>
          <xs:element ref="iodef:Contact"
                      minOccurs="0"/>
        </xs:sequence>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type" default="default"/>
        <xs:attribute name="severity"
                      type="iodef:severity-type"/>
        <xs:attribute name="action"
                      type="iodef:action-type" default="other"/>
        <xs:attribute name="ext-action"
                      type="xs:string" use="optional"/>
      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   ===  Method class                                                ===
   ====================================================================
  -->
    <xs:element name="Method">
      <xs:complexType>
        <xs:sequence>
          <xs:choice maxOccurs="unbounded">



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            <xs:element ref="iodef:Reference"/>
            <xs:element ref="iodef:Description"/>
          </xs:choice>
          <xs:element ref="iodef:AdditionalData"
                      minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type"/>
      </xs:complexType>
    </xs:element>
    <xs:element name="Reference">
      <xs:complexType>
        <xs:sequence>
          <xs:element name="ReferenceName"
                      type="iodef:MLStringType"/>
          <xs:element ref="iodef:URL"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Description"
                      minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   ===  Assessment class                                            ===
   ====================================================================
  -->
    <xs:element name="Assessment">
      <xs:complexType>
        <xs:sequence>
          <xs:choice maxOccurs="unbounded">
            <xs:element ref="iodef:Impact"/>
            <xs:element ref="iodef:TimeImpact"/>
            <xs:element ref="iodef:MonetaryImpact"/>
          </xs:choice>
          <xs:element ref="iodef:Counter"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Confidence" minOccurs="0"/>
          <xs:element ref="iodef:AdditionalData"
                      minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="occurrence">
          <xs:simpleType>
            <xs:restriction base="xs:NMTOKEN">
              <xs:enumeration value="actual"/>
              <xs:enumeration value="potential"/>
            </xs:restriction>
          </xs:simpleType>



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        </xs:attribute>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type"/>
      </xs:complexType>
    </xs:element>
    <xs:element name="Impact">
      <xs:complexType>
        <xs:simpleContent>
          <xs:extension base="iodef:MLStringType">
            <xs:attribute name="severity"
                          type="iodef:severity-type"/>
            <xs:attribute name="completion">
              <xs:simpleType>
                <xs:restriction base="xs:NMTOKEN">
                  <xs:enumeration value="failed"/>
                  <xs:enumeration value="succeeded"/>
                </xs:restriction>
              </xs:simpleType>
            </xs:attribute>
            <xs:attribute name="type"
                          use="optional" default="unknown">
              <xs:simpleType>
                <xs:restriction base="xs:NMTOKEN">
                  <xs:enumeration value="admin"/>
                  <xs:enumeration value="dos"/>
                  <xs:enumeration value="extortion"/>
                  <xs:enumeration value="file"/>
                  <xs:enumeration value="info-leak"/>
                  <xs:enumeration value="misconfiguration"/>
                  <xs:enumeration value="recon"/>
                  <xs:enumeration value="policy"/>
                  <xs:enumeration value="social-engineering"/>
                  <xs:enumeration value="user"/>
                  <xs:enumeration value="unknown"/>
                  <xs:enumeration value="ext-value"/>
                </xs:restriction>
              </xs:simpleType>
            </xs:attribute>
            <xs:attribute name="ext-type"
                          type="xs:string" use="optional"/>
          </xs:extension>
        </xs:simpleContent>
      </xs:complexType>
    </xs:element>
    <xs:element name="TimeImpact">
      <xs:complexType>
        <xs:simpleContent>
          <xs:extension base="iodef:PositiveFloatType">



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            <xs:attribute name="severity"
                          type="iodef:severity-type"/>
            <xs:attribute name="metric"
                          use="required">
              <xs:simpleType>
                <xs:restriction base="xs:NMTOKEN">
                  <xs:enumeration value="labor"/>
                  <xs:enumeration value="elapsed"/>
                  <xs:enumeration value="downtime"/>
                  <xs:enumeration value="ext-value"/>
                </xs:restriction>
              </xs:simpleType>
            </xs:attribute>
            <xs:attribute name="ext-metric"
                          type="xs:string" use="optional"/>
            <xs:attribute name="duration"
                          type="iodef:duration-type"/>
            <xs:attribute name="ext-duration"
                          type="xs:string" use="optional"/>
          </xs:extension>
        </xs:simpleContent>
      </xs:complexType>
    </xs:element>
    <xs:element name="MonetaryImpact">
      <xs:complexType>
        <xs:simpleContent>
          <xs:extension base="iodef:PositiveFloatType">
            <xs:attribute name="severity"
                          type="iodef:severity-type"/>
            <xs:attribute name="currency"
                          type="xs:string"/>
          </xs:extension>
        </xs:simpleContent>
      </xs:complexType>
    </xs:element>
    <xs:element name="Confidence">
      <xs:complexType mixed="true">
        <xs:attribute name="rating" use="required">
          <xs:simpleType>
            <xs:restriction base="xs:NMTOKEN">
              <xs:enumeration value="low"/>
              <xs:enumeration value="medium"/>
              <xs:enumeration value="high"/>
              <xs:enumeration value="numeric"/>
              <xs:enumeration value="unknown"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>



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      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   === EventData class                                              ===
   ====================================================================
  -->
    <xs:element name="EventData">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:Description"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:DetectTime"
                      minOccurs="0"/>
          <xs:element ref="iodef:StartTime"
                      minOccurs="0"/>
          <xs:element ref="iodef:EndTime"
                      minOccurs="0"/>
          <xs:element ref="iodef:Contact"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Assessment"
                      minOccurs="0"/>
          <xs:element ref="iodef:Method"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Flow"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Expectation"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Record"
                      minOccurs="0"/>
          <xs:element ref="iodef:EventData"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:AdditionalData"
                      minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type" default="default"/>
      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   ===  Flow class                                                ===
   ====================================================================
  -->
    <xs:element name="Flow">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:System"



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                      maxOccurs="unbounded"/>
        </xs:sequence>
      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   ===  System class                                                ===
   ====================================================================
  -->
    <xs:element name="System">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:Node"/>
          <xs:element ref="iodef:Service"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:OperatingSystem"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Counter"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Description"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:AdditionalData"
                      minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="restriction"
                     type="iodef:restriction-type"/>
        <xs:attribute name="interface"
                      type="xs:string"/>
        <xs:attribute name="category">
          <xs:simpleType>
            <xs:restriction base="xs:NMTOKEN">
              <xs:enumeration value="source"/>
              <xs:enumeration value="target"/>
              <xs:enumeration value="intermediate"/>
              <xs:enumeration value="sensor"/>
              <xs:enumeration value="infrastructure"/>
              <xs:enumeration value="ext-value"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
        <xs:attribute name="ext-category"
                      type="xs:string" use="optional"/>
        <xs:attribute name="spoofed"
                      default="unknown">
          <xs:simpleType>
            <xs:restriction base="xs:NMTOKEN">
              <xs:enumeration value="unknown"/>
              <xs:enumeration value="yes"/>



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              <xs:enumeration value="no"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
      </xs:complexType>
    </xs:element>
  <!--
  ====================================================================
  === Node class                                                   ===
  ====================================================================
  -->
    <xs:element name="Node">
      <xs:complexType>
        <xs:sequence>
          <xs:choice maxOccurs="unbounded">
            <xs:element name="NodeName"
                        type="iodef:MLStringType" minOccurs="0"/>
            <xs:element ref="iodef:Address"
                        minOccurs="0" maxOccurs="unbounded"/>
          </xs:choice>
          <xs:element ref="iodef:Location"
                      minOccurs="0"/>
          <xs:element ref="iodef:DateTime"
                      minOccurs="0"/>
          <xs:element ref="iodef:NodeRole"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Counter"
                      minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
      </xs:complexType>
    </xs:element>
    <xs:element name="Address">
      <xs:complexType>
        <xs:simpleContent>
          <xs:extension base="xs:string">
            <xs:attribute name="category" default="ipv4-addr">
              <xs:simpleType>
                <xs:restriction base="xs:NMTOKEN">
                  <xs:enumeration value="asn"/>
                  <xs:enumeration value="atm"/>
                  <xs:enumeration value="e-mail"/>
                  <xs:enumeration value="mac"/>
                  <xs:enumeration value="ipv4-addr"/>
                  <xs:enumeration value="ipv4-net"/>
                  <xs:enumeration value="ipv4-net-mask"/>
                  <xs:enumeration value="ipv6-addr"/>
                  <xs:enumeration value="ipv6-net"/>
                  <xs:enumeration value="ipv6-net-mask"/>



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                  <xs:enumeration value="ext-value"/>
                </xs:restriction>
              </xs:simpleType>
            </xs:attribute>
            <xs:attribute name="ext-category"
                          type="xs:string" use="optional"/>
            <xs:attribute name="vlan-name"
                          type="xs:string"/>
            <xs:attribute name="vlan-num"
                          type="xs:integer"/>
          </xs:extension>
        </xs:simpleContent>
      </xs:complexType>
    </xs:element>
    <xs:element name="Location" type="iodef:MLStringType"/>
    <xs:element name="NodeRole">
      <xs:complexType>
        <xs:simpleContent>
          <xs:extension base="iodef:MLStringType">
            <xs:attribute name="category" use="required">
              <xs:simpleType>
                <xs:restriction base="xs:NMTOKEN">
                  <xs:enumeration value="client"/>
                  <xs:enumeration value="server-internal"/>
                  <xs:enumeration value="server-public"/>
                  <xs:enumeration value="www"/>
                  <xs:enumeration value="mail"/>
                  <xs:enumeration value="messaging"/>
                  <xs:enumeration value="streaming"/>
                  <xs:enumeration value="voice"/>
                  <xs:enumeration value="file"/>
                  <xs:enumeration value="ftp"/>
                  <xs:enumeration value="p2p"/>
                  <xs:enumeration value="name"/>
                  <xs:enumeration value="directory"/>
                  <xs:enumeration value="credential"/>
                  <xs:enumeration value="print"/>
                  <xs:enumeration value="application"/>
                  <xs:enumeration value="database"/>
                  <xs:enumeration value="infra"/>
                  <xs:enumeration value="log"/>
                  <xs:enumeration value="ext-value"/>
                </xs:restriction>
              </xs:simpleType>
            </xs:attribute>
            <xs:attribute name="ext-category"
                          type="xs:string" use="optional"/>
          </xs:extension>



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        </xs:simpleContent>
      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   ===  Service Class                                               ===
   ====================================================================
  -->
    <xs:element name="Service">
      <xs:complexType>
        <xs:sequence>
          <xs:choice minOccurs="0">
            <xs:element name="Port"
                        type="xs:integer"/>
            <xs:element name="Portlist"
                        type="iodef:PortlistType"/>
          </xs:choice>
          <xs:element name="ProtoType"
                      type="xs:integer" minOccurs="0"/>
          <xs:element name="ProtoCode"
                      type="xs:integer" minOccurs="0"/>
          <xs:element name="ProtoField"
                      type="xs:integer" minOccurs="0"/>
          <xs:element ref="iodef:Application"
                      minOccurs="0"/>
        </xs:sequence>
        <xs:attribute name="ip_protocol"
                      type="xs:integer" use="required"/>
      </xs:complexType>
    </xs:element>
    <xs:simpleType name="PortlistType">
      <xs:restriction base="xs:string">
        <xs:pattern value="\d+(\-\d+)?(,\d+(\-\d+)?)*"/>
      </xs:restriction>
    </xs:simpleType>
  <!--
   ====================================================================
   ===  Counter class                                              ===
   ====================================================================
  -->
    <xs:element name="Counter">
      <xs:complexType>
        <xs:simpleContent>
          <xs:extension base="xs:double">
            <xs:attribute name="type" use="required">
              <xs:simpleType>
                <xs:restriction base="xs:NMTOKEN">
                  <xs:enumeration value="byte"/>



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                  <xs:enumeration value="packet"/>
                  <xs:enumeration value="flow"/>
                  <xs:enumeration value="session"/>
                  <xs:enumeration value="event"/>
                  <xs:enumeration value="alert"/>
                  <xs:enumeration value="message"/>
                  <xs:enumeration value="host"/>
                  <xs:enumeration value="site"/>
                  <xs:enumeration value="organization"/>
                  <xs:enumeration value="ext-value"/>
                </xs:restriction>
              </xs:simpleType>
            </xs:attribute>
            <xs:attribute name="ext-type"
                          type="xs:string" use="optional"/>
            <xs:attribute name="meaning"
                          type="xs:string" use="optional"/>
            <xs:attribute name="duration"
                          type="iodef:duration-type"/>
            <xs:attribute name="ext-duration"
                          type="xs:string" use="optional"/>
          </xs:extension>
        </xs:simpleContent>
      </xs:complexType>
    </xs:element>
  <!--
   ====================================================================
   ===  Record class                                                ===
   ====================================================================
  -->
    <xs:element name="Record">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:RecordData"
                      maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type"/>
      </xs:complexType>
    </xs:element>
    <xs:element name="RecordData">
      <xs:complexType>
        <xs:sequence>
          <xs:element ref="iodef:DateTime"
                      minOccurs="0"/>
          <xs:element ref="iodef:Description"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Application"



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                      minOccurs="0"/>
          <xs:element ref="iodef:RecordPattern"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:RecordItem"
                      maxOccurs="unbounded"/>
          <xs:element ref="iodef:AdditionalData"
                      minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type"/>
      </xs:complexType>
    </xs:element>
    <xs:element name="RecordPattern">
      <xs:complexType>
        <xs:simpleContent>
          <xs:extension base="xs:string">
            <xs:attribute name="type" use="required">
              <xs:simpleType>
                <xs:restriction base="xs:NMTOKEN">
                  <xs:enumeration value="regex"/>
                  <xs:enumeration value="binary"/>
                  <xs:enumeration value="xpath"/>
                  <xs:enumeration value="ext-value"/>
                </xs:restriction>
              </xs:simpleType>
            </xs:attribute>
            <xs:attribute name="ext-type"
                          type="xs:string" use="optional"/>
            <xs:attribute name="offset"
                          type="xs:integer" use="optional"/>
            <xs:attribute name="offsetunit"
                          use="optional" default="line">
              <xs:simpleType>
                <xs:restriction base="xs:NMTOKEN">
                  <xs:enumeration value="line"/>
                  <xs:enumeration value="byte"/>
                  <xs:enumeration value="ext-value"/>
                </xs:restriction>
              </xs:simpleType>
            </xs:attribute>
            <xs:attribute name="ext-offsetunit"
                          type="xs:string" use="optional"/>
            <xs:attribute name="instance"
                          type="xs:integer" use="optional"/>
          </xs:extension>
        </xs:simpleContent>
      </xs:complexType>
    </xs:element>



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    <xs:element name="RecordItem"
                type="iodef:ExtensionType"/>
  <!--
   ====================================================================
   ===  Classes that describe software                       ===
   ====================================================================
  -->
    <xs:complexType name="SoftwareType">
      <xs:sequence>
        <xs:element ref="iodef:URL"
                    minOccurs="0"/>
      </xs:sequence>
      <xs:attribute name="swid"
                    type="xs:string" default="0"/>
      <xs:attribute name="configid"
                    type="xs:string" default="0"/>
      <xs:attribute name="vendor"
                    type="xs:string"/>
      <xs:attribute name="family"
                    type="xs:string"/>
      <xs:attribute name="name"
                    type="xs:string"/>
      <xs:attribute name="version"
                    type="xs:string"/>
      <xs:attribute name="patch"
                    type="xs:string"/>
    </xs:complexType>
    <xs:element name="Application"
                type="iodef:SoftwareType"/>
    <xs:element name="OperatingSystem"
                type="iodef:SoftwareType"/>
  <!--
   ====================================================================
   === Miscellaneous simple classes                                 ===
   ====================================================================
  -->
    <xs:element name="Description"
                type="iodef:MLStringType"/>
    <xs:element name="URL"
                type="xs:anyURI"/>
  <!--
   ====================================================================
   === Data Types                                           ===
   ====================================================================
  -->
    <xs:simpleType name="PositiveFloatType">
      <xs:restriction base="xs:float">
        <xs:minExclusive value="0"/>



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      </xs:restriction>
    </xs:simpleType>
    <xs:complexType name="MLStringType">
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="lang"
                        type="xs:language" use="optional"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
    <xs:complexType name="ExtensionType" mixed="true">
      <xs:sequence>
        <xs:any namespace="##any" processContents="lax"
                minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="dtype"
                    type="iodef:dtype-type" use="required"/>
      <xs:attribute name="ext-dtype"
                    type="xs:string" use="optional"/>
      <xs:attribute name="meaning"
                    type="xs:string"/>
      <xs:attribute name="formatid"
                    type="xs:string"/>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type"/>
    </xs:complexType>
  <!--
   ====================================================================
   === Global attribute type declarations                          ===
   ====================================================================
  -->
    <xs:simpleType name="restriction-type">
      <xs:restriction base="xs:NMTOKEN">
        <xs:enumeration value="default"/>
        <xs:enumeration value="public"/>
        <xs:enumeration value="need-to-know"/>
        <xs:enumeration value="private"/>
      </xs:restriction>
    </xs:simpleType>

    <xs:simpleType name="severity-type">
      <xs:restriction base="xs:NMTOKEN">
        <xs:enumeration value="low"/>
        <xs:enumeration value="medium"/>
        <xs:enumeration value="high"/>
      </xs:restriction>
    </xs:simpleType>




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    <xs:simpleType name="duration-type">
      <xs:restriction base="xs:NMTOKEN">
        <xs:enumeration value="second"/>
        <xs:enumeration value="minute"/>
        <xs:enumeration value="hour"/>
        <xs:enumeration value="day"/>
        <xs:enumeration value="month"/>
        <xs:enumeration value="quarter"/>
        <xs:enumeration value="year"/>
        <xs:enumeration value="ext-value"/>
      </xs:restriction>
    </xs:simpleType>

    <xs:simpleType name="action-type">
      <xs:restriction base="xs:NMTOKEN">
        <xs:enumeration value="nothing"/>
        <xs:enumeration value="contact-source-site"/>
        <xs:enumeration value="contact-target-site"/>
        <xs:enumeration value="contact-sender"/>
        <xs:enumeration value="investigate"/>
        <xs:enumeration value="block-host"/>
        <xs:enumeration value="block-network"/>
        <xs:enumeration value="block-port"/>
        <xs:enumeration value="rate-limit-host"/>
        <xs:enumeration value="rate-limit-network"/>
        <xs:enumeration value="rate-limit-port"/>
        <xs:enumeration value="remediate-other"/>
        <xs:enumeration value="status-triage"/>
        <xs:enumeration value="status-new-info"/>
        <xs:enumeration value="other"/>
        <xs:enumeration value="ext-value"/>
      </xs:restriction>
    </xs:simpleType>

    <xs:simpleType name="dtype-type">
      <xs:restriction base="xs:NMTOKEN">
        <xs:enumeration value="boolean"/>
        <xs:enumeration value="byte"/>
        <xs:enumeration value="character"/>
        <xs:enumeration value="date-time"/>
        <xs:enumeration value="integer"/>
        <xs:enumeration value="ntpstamp"/>
        <xs:enumeration value="portlist"/>
        <xs:enumeration value="real"/>
        <xs:enumeration value="string"/>
        <xs:enumeration value="file"/>
        <xs:enumeration value="path"/>
        <xs:enumeration value="frame"/>



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        <xs:enumeration value="packet"/>
        <xs:enumeration value="ipv4-packet"/>
        <xs:enumeration value="ipv6-packet"/>
        <xs:enumeration value="url"/>
        <xs:enumeration value="csv"/>
        <xs:enumeration value="winreg"/>
        <xs:enumeration value="xml"/>
        <xs:enumeration value="ext-value"/>
      </xs:restriction>
    </xs:simpleType>
  </xs:schema>

9.  Security Considerations

   The IODEF data model itself does not directly introduce security
   issues.  Rather, it simply defines a representation for incident
   information.  As the data encoded by the IODEF might be considered
   privacy sensitive by the parties exchanging the information or by
   those described by it, care needs to be taken in ensuring the
   appropriate disclosure during both document exchange and subsequent
   processing.  The former must be handled by a messaging format, but
   the latter risk must be addressed by the systems that process, store,
   and archive IODEF documents and information derived from them.

   The contents of an IODEF document may include a request for action or
   an IODEF parser may independently have logic to take certain actions
   based on information that it finds.  For this reason, care must be
   taken by the parser to properly authenticate the recipient of the
   document and ascribe an appropriate confidence to the data prior to
   action.

   The underlying messaging format and protocol used to exchange
   instances of the IODEF MUST provide appropriate guarantees of
   confidentiality, integrity, and authenticity.  The use of a
   standardized security protocol is encouraged.  The Real-time Inter-
   network Defense (RID) protocol [18] and its associated transport
   binding IODEF/RID over SOAP [19] provide such security.

   In order to suggest data processing and handling guidelines of the
   encoded information, the IODEF allows a document sender to convey a
   privacy policy using the restriction attribute.  The various
   instances of this attribute allow different data elements of the
   document to be covered by dissimilar policies.  While flexible, it
   must be stressed that this approach only serves as a guideline from
   the sender, as the recipient is free to ignore it.  The issue of
   enforcement is not a technical problem.





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10.  IANA Considerations

   This document uses URNs to describe an XML namespace and schema
   conforming to a registry mechanism described in [15]

   Registration for the IODEF namespace:

   o  URI: urn:ietf:params:xml:ns:iodef-1.0

   o  Registrant Contact: See the first author of the "Author's Address"
      section of this document.

   o  XML: None.  Namespace URIs do not represent an XML specification.

   Registration for the IODEF XML schema:

   o  URI: urn:ietf:params:xml:schema:iodef-1.0

   o  Registrant Contact: See the first author of the "Author's Address"
      section of this document.

   o  XML: See the "IODEF Schema" in Section 8 of this document.

11.  Acknowledgments

   The following groups and individuals, listed alphabetically,
   contributed substantially to this document and should be recognized
   for their efforts.

   o  Patrick Cain, Cooper-Cain Group, Inc.

   o  The eCSIRT.net Project

   o  The Incident Object Description and Exchange Format Working-Group
      of the TERENA task-force (TF-CSIRT)

   o  Glenn Mansfield Keeni, Cyber Solutions, Inc.

   o  Hiroyuki Kido, NARA Institute of Science and Technology

   o  Kathleen Moriarty, MIT Lincoln Laboratory

   o  Brian Trammell, CERT/NetSA








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12.  References

12.1.  Normative References

   [1]   World Wide Web Consortium, "Extensible Markup Language (XML)
         1.0 (Second Edition)", W3C Recommendation , October 2000,
         <http://www.w3.org/TR/2000/REC-xml-20001006>.

   [2]   World Wide Web Consortium, "XML XML Schema Part 1: Structures
         Second Edition", W3C Recommendation , October 2004,
         <http://www.w3.org/TR/xmlschema-1/>.

   [3]   World Wide Web Consortium, "XML Schema Part 2: Datatypes Second
         Edition", W3C Recommendation , October 2004,
         <http://www.w3.org/TR/xmlschema-2/>.

   [4]   World Wide Web Consortium, "Namespaces in XML", W3C
         Recommendation , January 1999,
         <http://www.w3.org/TR/REC-xml-names/>.

   [5]   World Wide Web Consortium, "XML Path Language (XPath) 2.0", W3C
         Candidate Recommendation , June 2006,
         <http://www.w3.org/TR/xpath20/>.

   [6]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
         Levels", RFC 2119, March 1997.

   [7]   Philips, A. and M. Davis, "Tags for Identifying of Languages",
         RFC 4646, September 2006.

   [8]   Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
         Resource Identifiers (URI): Generic Syntax", RFC 3986,
         January 2005`.

   [9]   Freed, N. and J. Postel, "IANA Charset Registration
         Procedures", BCP 2978, October 2000.

   [10]  Sciberras, A., "Schema for User Applications", RFC 4519,
         June 2006.

   [11]  Resnick, P., "Internet Message Format", RFC 2822, April 2001.

   [12]  Klyne, G. and C. Newman, "Date and Time on the Internet:
         Timestamps", RFC 3339, July 2002.







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   [13]  International Organization for Standardization, "International
         Standard: Data elements and interchange formats - Information
         interchange - Representation of dates and times", ISO 8601,
         Second Edition, December 2000.

   [14]  International Organization for Standardization, "International
         Standard: Codes for the representation of currencies and funds,
         ISO 4217:2001", ISO 4217:2001, August 2001.

   [15]  Mealling, M., "The IETF XML Registry", RFC 3688, January 2004.

12.2.  Informative References

   [16]  Keeni, G., Demchenko, Y., and R. Danyliw, "Requirements for the
         Format for Incident Information Exchange (FINE)", Work
         in Progress, June 2006.

   [17]  Debar, H., Curry, D., Debar, H., and B. Feinstein, "Intrusion
         Detection Message Exchange Format", RFC 4765, March 2007.

   [18]  Moriarty, K., "Real-time Inter-network Defense", Work
         in Progress, April 2007.

   [19]  Moriarty, K. and B. Trammell, "IODEF/RID over SOAP", Work
         in Progress, April 2007.

   [20]  Shafranovich, Y., "Common Format and MIME Type for Comma-
         Separated Values (CSV) File", RFC 4180, October 2005.























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Authors' Addresses

   Roman Danyliw
   CERT - Software Engineering Institute
   Pittsburgh, PA
   USA

   EMail: rdd@cert.org


   Jan Meijer

   EMail: jan@flyingcloggies.nl


   Yuri Demchenko
   University of Amsterdam
   Amsterdam
   Netherlands

   EMail: demch@chello.nl






























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Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
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   The IETF takes no position regarding the validity or scope of any
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   this document or the extent to which any license under such rights
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   Copies of IPR disclosures made to the IETF Secretariat and any
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   The IETF invites any interested party to bring to its attention any
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   ietf-ipr@ietf.org.












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