mile Working Group                                           B. Trammell
Internet-Draft                                                ETH Zurich
Intended status: BCP                                   February 16, 17, 2012
Expires: August 19, 20, 2012

              Guidelines for Defining Extensions to IODEF for Managed Incident Lightweight


   This document provides guidelines for extensions to IODEF [RFC5070]
   for exchange of incident management data, and contains a template for
   Internet-Drafts describing those extensions, in order to ease the
   work and improve the quality of extension descriptions.  It also
   specifies additional Expert Review of XML Schemas used to describe
   these extensions.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 19, 20, 2012.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Applicability of Extensions to IODEF . . . . . . . . . . . . .  3
   4.  Selecting a Mechanism for IODEF Extension  . . . . . . . . . .  4
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  6
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  6
   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  6
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     8.1.  Normative References . . . . . . . . . . . . . . . . . . .  6
     8.2.  Informative References . . . . . . . . . . . . . . . . . .  7
   Appendix A.  Document Template . . . . . . . . . . . . . . . . . .  7
     A.1.  Introduction . . . . . . . . . . . . . . . . . . . . . . .  7
     A.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  7  8
     A.3.  Applicability  . . . . . . . . . . . . . . . . . . . . . .  8
     A.4.  Extension Definition . . . . . . . . . . . . . . . . . . .  8
       A.4.1.  IODEF Data Types . . . . . . . . . . . . . . . . . . .  9
     A.5.  Security Considerations  . . . . . . . . . . . . . . . . . 10
     A.6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . 10
     A.7.  Appendix A: XML Schema Definition for Extension  . . . . . 11
     A.8.  Appendix B: Examples . . . . . . . . . . . . . . . . . . . 11
   Appendix B.  Example Enumerated Type Extension Definition:
                E.164 Address . . . . . . . . . . . . . . . . . . . . 11 12
   Appendix C.  Example Element Definition: Test  . . . . . . . . . . 12
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.  Introduction

   In the five years since the specification of IODEF [RFC5070], the
   threat environment has evolved, as has the practice of cooperative
   network defense.  These trends, along with experience gained through
   implementation and deployment, have indicated the need to extend
   IODEF.  This document provides guidelines for defining these
   extensions.  It starts by describing the applicability of IODEF
   extensions, and the IODEF extension mechanisms, before providing a
   section Appendix A that is itself designed to be copied out and
   filled in as the starting point of an Internet-Draft about an IODEF

   Additionally, IODEF extensions through AdditionalData and RecordItem
   elements, as per section 5.2 of [RFC5070], generally register their
   namespaces and schemas with the IANA XML Namespace registry at and the IANA XML
   Schema registry at,
   respectively [RFC3688].  In addition to schema reviews required by
   IANA, these registry requests should be accompanied by a review by
   IODEF experts to ensure the specified AdditionalData and/or
   RecordItem contents are compatible with IODEF and with other existing
   IODEF extensions.  This document specifies that review in Section 5. 6.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

3.  Applicability of Extensions to IODEF

   Before deciding to extend IODEF, the first step is to determine
   whether an IODEF extension is a good fit for a given problem.  There
   are two sides to this question:

   1.  Does the problem involve the reporting or sharing of information
       about an incident?  "Incident" is not defined in the terminology
       for IODEF, but for purposes of IODEF can be loosely described as
       "something that happened that has some impact on the information
       security situation of an entity", with quite a bit of leeway for
       interpretation.  If the answer to this question is unequivocally
       "No", then IODEF is probably not a good choice as a base
       technology for the application area.

   2.  Can IODEF adequately represent information about the incident
       without extension?  IODEF has a reasonably rich set of incident-
       relevant classes.  If, after examination of the problem area and
       the IODEF specification, the answer to this question is "Yes",
       then extension is not necessary.

   A non-exhaustive list of good candidate extensions to IODEF includes:

   o  Leveraging existing work in describing aspects of incidents to
      make IODEF more expressive, by standardized reference to external
      information bases about incidents and incident-related information

   o  Allowing the description of new types of entities (e.g., related
      actors) or new types of characteristics of entities (e.g.,
      information related to financial services) involved in an IODEF
      incident report

   o  Allowing additional semantic or metadata labeling of IODEF
      Documents (e.g., for handling or disposition instructions, or
      compliance with data protection and data retention regulations)


4.  Selecting a Mechanism for IODEF Extension

   IODEF was designed to be extended through any combination of:

   1.  extending the enumerated values of Attributes, as per section 5.1
       of [RFC5070];

   2.  class extension through AdditionalData and RecordItem elements,
       as per section 5.2 of [RFC5070]; and/or

   3.  containment of the IODEF-Document element within an external XML
       Document, itself containing extension data.

   Note that in this final case, the extension will not be directly
   interoperable with IODEF implementations, and must "unwrap" the IODEF
   document from its container; nevertheless, this may be appropriate
   for certain use cases involving integration with IODEF within
   external schemas.  Extensions using containment of an IODEF-Document
   are not further treated in this document, though the document
   template in Appendix A may be of some use in defining them.

   Certain attributes containing enumerated values within certain IODEF
   elements may be extended.  For an attribute named "foo", this is
   achieved by giving the value of "foo" as "ext-value", and adding a
   new attribute named "ext-foo" containing the extended value.  The
   attributes which can be extended in this way are defined in Section
   5.1 of [RFC5070], and limited to the following:

   o  Incident@purpose

   o  Contact@role

   o  Contact@type

   o  RegistryHandle@registry

   o  Impact@type

   o  TimeImpact@metric

   o  TimeImpact@duration

   o  HistoryItem@action

   o  Expectation@action

   o  System@category

   o  Counter@type

   o  Counter@duration

   o  Address@category

   o  NodeRole@category

   o  RecordPattern@type

   o  RecordPattern@offsetunit

   o  AdditionalData@dtype

   o  RecordItem@dtype

   An example definition of an attribute extension is given in
   Appendix B.

   IODEF documents can contain extended scalar or XML data using an
   AdditionalData element or a RecordItem element.  Scalar data
   extensions MUST set the "dtype" attribute of the containing element
   to the data type to reference one of the IODEF data types as
   enumerated in Appendix A.4.1, and SHOULD define the use the "meaning"
   and "formatid" attributes to explain the content of the element.

   XML extensions within an AdditionalData or RecordItem element use a
   dtype of "xml", and SHOULD define a schema for the root element
   within the AdditionalData or RecordItem attribute.  An example
   definition of an element definition is given in Appendix C.


5.  Security Considerations

   This document defines a template for extensions to IODEF; the
   security considerations for IODEF [RFC5070] apply.


6.  IANA Considerations

   Changes to the XML Schema registry for schema names beginning with
   "urn:ietf:params:xml:schema:iodef" are subject to an additional IODEF
   Expert Review [RFC5226].  The IODEF expert(s) for these reviews will
   be designated by the IETF Security Area Directors.

   [IANA NOTE: The authors request that IANA include a note at the top
   of, stating
   "Changes to the XML Schema registry for schema names beginning with
   'urn:ietf:params:xml:schema:iodef' are subject to an additional IODEF
   Expert Review [RFC5226]," and naming the designated expert.]


7.  Acknowledgments

   Thanks to David Black, Takeshi Takahashi, Tom Millar, and Kathleen
   Moriarty for their comments.  This work is materially supported by
   the European Union Seventh Framework Program under grant agreement
   257315 (DEMONS).


8.  References


8.1.  Normative References

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

   [RFC5070]  Danyliw, R., Meijer, J., and Y. Demchenko, "The Incident
              Object Description Exchange Format", RFC 5070,
              December 2007.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.


              Moriarty, K., "Real-time Inter-network Defense (RID)",
              RFC 6045, November 2010.

              draft-ietf-mile-rfc6045-bis-11 (work in progress),
              January 2012.

8.2.  Informative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.


   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 2373, July 1998.

   [RFC2396] 4291, February 2006.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifiers Identifier (URI): Generic Syntax", STD 66,
              RFC 2396,
              August 1998.

   [RFC2822] 3986, January 2005.

   [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 2822,
              April 2001. 5322,
              October 2008.

   [RFC3339]  Klyne, G., Ed. and C. Newman, "Date and Time on the
              Internet: Timestamps", RFC 3339, July 2002.

   [RFC3552]  Rescorla, E. and B. Korver, "Guidelines for Writing RFC
              Text on Security Considerations", BCP 72, RFC 3552,
              July 2003.

   [RFC4519]  Sciberras, A., "Lightweight Directory Access Protocol
              (LDAP): Schema for User Applications", RFC 4519,
              June 2006.

   [RFC6116]  Bradner, S., Conroy, L., and K. Fujiwara, "The E.164 to
              Uniform Resource Identifiers (URI) Dynamic Delegation
              Discovery System (DDDS) Application (ENUM)", RFC 6116,
              March 2011.

Appendix A.  Document Template

   The document template given in this section is provided as a starting
   point for writing an Internet-Draft describing an IODEF extension.

A.1.  Introduction

   The introduction section introduces the problem being solved by the
   extension, and motivates the development and deployment of the

A.2.  Terminology

   The terminology section introduces and defines terms specific to the
   document.  Terminology from [RFC5070] or [RFC6045] [I-D.ietf-mile-rfc6045-bis]
   should be referenced in this section, but not redefined or copied.
   If [RFC2119] terms are used in the document, this should be noted in
   the terminology section.

A.3.  Applicability

   The applicability section defines the use cases to which the
   extension is applicable, and details any requirements analysis done
   during the development of the extension.  The primary goal of this
   section is to allow readers to see if an extension is indeed intended
   to solve a particular problem.  This should also the scope of the
   extension, as appropriate, by pointing out any non-obvious situations
   to which it is not intended to apply.

   In addition to defining the applicability, this section may also
   present example situations, which should then be detailed in the
   examples section, below.

A.4.  Extension Definition

   This section defines the extension.

   Extensions to enumerated types are defined in one subsection for each
   attribute to be extended, enumerating the new values with an
   explanation of the meaning of the new value.  An example enumeration
   extension is shown in Appendix B, below.

   Element extensions are defined in one subsection for each element, in
   top-down order, from the element contained within AdditionalData or
   RecordItem; an example element extension is shown in Appendix C,
   below.  Each element should be described by a UML diagram as in
   Figure 1, followed by a description of each of the attributes, and a
   short description of each of the child elements.  Child elements
   should then be defined in a subsequent subsection, if not already
   defined in the IODEF document itself, or in another referenced MILE
   extension document.

   | Element             |
   | TYPE attribute0     |<>----------[ChildExactlyOne]
   | TYPE attribute1     |<>--{0..1}--[ChildZeroOrOne]
   |                     |<>--{0..*}--[ChildZeroOrMore]
   |                     |<>--{1..*}--[ChildOneOrMore]

                   Figure 1: Example UML Element Diagram

   Elements containing child elements should indicate the multiplicity
   of those child elements, as shown in the figure above.  Allowable
   TYPEs are discussed in the following subsection.

A.4.1.  IODEF Data Types

   The allowable TYPEs for attributes within IODEF are enumerated in
   section 2 of [RFC5070], and consist of:


   o  REAL


   o  STRING

   o  ML_STRING (for strings in encodings other than that of the
      enclosing document)

   o  BYTE for bytes or byte vectors in Base 64 encoding

   o  HEXBIN for bytes in ascii-hexadecimal encoding

   o  ENUM for enumerated types; allowable values of the enumeration
      must be defined in the attribute definition

   o  DATETIME for ISO 8601:2000 [RFC3339] encoded timestamps

   o  TIMEZONE for timezones as encoded in section 2.9 of [RFC5070].

   o  PORTLIST for port lists as encoded in section 2.10 of [RFC5070].

   o  POSTAL for postal addresses as defined in section 2.23 of

   o  NAME for names of natural or legal persons as defined in section
      2.3 of [RFC4519].

   o  PHONE for telephone numbers as defined in section 2.35 of

   o  EMAIL for email addresses as defined in section 3.4.1. of

   o  URL for URLs as in [RFC2396]. [RFC3986].

   In addition to these simple data types, IODEF provides a compound
   data type for representing network address information.  Addresses
   included within an extension element should be represented by
   containing an IODEF:Address element, which supports IPv4 and
   [RFC4291] IPv6 addresses, as well as MAC, ATM, and BGP autonomous
   system numbers.  Application-layer addresses should be represented
   with the URL simple attribute type, instead.

A.5.  Security Considerations

   [SECDIR and RFC-EDITOR NOTE: Despite the title, this section is NOT a
   Security Considerations section, rather a template Security
   Considerations section for future extension documents to be built
   from this template.  See Section 4 5 for Security Considerations for
   this document.]

   Any security considerations [RFC3552] raised by this extension or its
   deployment should be detailed in this section.  Guidance should focus
   on ensuring the users of this extension do so in a secure fashion,
   with special attention to non-obvious implications of the
   transmission of the information represented by an extension.

   It should also be noted in this section that the security
   considerations for IODEF [RFC5070] apply to the extension as well.

A.6.  IANA Considerations

   [IANA and RFC-EDITOR NOTE: Despite the title, this section is NOT an
   IANA Considerations section, rather a template IANA Considerations
   section for future extension documents to be built from this
   template.  See Section 5 6 for IANA Considerations for this document.]

   Any IANA considerations [RFC5226] for the document should be detailed
   in this section; if none, the section should exist and contain the
   text "this document has no actions for IANA".

   IODEF Extensions which represent an enumeration should reference an
   existing IANA registry or subregistry for the values of that
   enumeration.  If no such registry exists, this section should define
   a new registry to hold the enumeration's values, and define the
   policies by which additions may be made to the registry.

   IODEF Extensions adding elements to the AdditionalData section of an
   IODEF document should register their own namespaces and schemas for
   extensions with IANA; therefore, this section should contain at least
   a registration request for the namespace and the schema, as follows,
   modified as appropriate for the extension:

   Registration request for the IODEF My-Extension namespace:

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

     Registrant Contact: Refer here to the authors' addresses section of
   the document, or to an organizational contact in the case of an
   extension supported by an external organization.

     XML: None

   Registration request for the IODEF My-Extension XML schema:

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

     Registrant Contact: Refer here to the authors' addresses section of
   the document, or to an organizational contact in the case of an
   extension supported by an external organization.

     XML: Refer here to the XML Schema in the appendix of the document,
   or to a well-known external reference in the case of an extension
   with an externally-defined schema.

A.7.  Appendix A: XML Schema Definition for Extension

   The XML Schema describing the elements defined in the Extension
   Defintion section is given here.  Each of the examples in section
   Appendix A.8 should be verified to validate against this schema by
   automated tools.

A.8.  Appendix B: Examples

   This section contains example IODEF-Documents illustrating the
   extension.  If example situations are outlined in the applicability
   section, documents for those examples should be provided in the same
   order as in the applicability section.  Example documents should be
   tested to validate against the schema given in the appendix.

Appendix B.  Example Enumerated Type Extension Definition: E.164 Address

   This example extends the IODEF Address element to support the
   encoding of ENUM-mapped telephone numbers [RFC6116].

   Attribute: Address@category

   Extended value(s): enum-e164

   Value meaning and format: An E.164 telephone number encoded as a
   domain name in the space, e.g.
   "" for +1 212 555 1212, as per section
   3.2 of [RFC6116].

   Additional considerations: none.

Appendix C.  Example Element Definition: Test

   This example defines the Test class for labeling IODEF test data.

   The Test class is intended to be included within an AdditionalData
   element in an IODEF Document.  If a Test element is present, it
   indicates that an IODEF Document contains test data, not a reference
   to a real incident.

   The Test class contains information about how the test data was

   | Test                |
   | ENUM category       |
   | STRING generator    |
   |                     |
   |                     |

                         Figure 2: The Test class

   The Test class has two attributes:

   category:   Required.  ENUM.  The type of test data.  The permitted
      values for this attribute are shown below.  The default value is

      1.  unspecified.  The document contains test data, but no further
          information is available.

      2.  internal.  The test data is intended for the internal use of
          an implementor, and should not be distributed or used outside
          the context in which it was generated.

      3.  unit.  The test data is intended for unit testing of an
          implementation, and may be included with the implementation to
          support this as part of the build and deployment process.

      4.  interoperability.  The test data is intended for
          interoperability testing of an implementation, and may be
          freely shared to support this purpose.

   generator:   Optional.  STRING.  A free-form string identifying the
      person, entity, or program which generated the test data.

Author's Address

   Brian Trammell
   Swiss Federal Institute of Technology Zurich
   Gloriastrasse 35
   8092 Zurich

   Phone: +41 44 632 70 13