datatracker.ietf.org
Sign in
Version 5.3.0, 2014-04-12
Report a bug

IODEF-extension for structured cybersecurity information
draft-ietf-mile-sci-13

Document type: Active Internet-Draft (mile WG)
Document stream: IETF
Last updated: 2014-02-04 (latest revision 2014-01-14)
Intended RFC status: Proposed Standard
Other versions: plain text, pdf, xml, html

IETF State: Submitted to IESG for Publication Aug 2013
Consensus: Unknown
Document shepherd: Brian Trammell
Shepherd Write-Up: Last changed 2013-10-03

IESG State: RFC Ed Queue
IANA Action State: RFC-Ed-Ack
RFC Editor State: AUTH48
Responsible AD: Sean Turner
Send notices to: mile-chairs@tools.ietf.org, draft-ietf-mile-sci@tools.ietf.org

MILE Working Group                                          T. Takahashi
Internet-Draft                                                      NICT
Intended status: Standards Track                            K. Landfield
Expires: July 18, 2014                                            McAfee
                                                               T. Millar
                                                                  USCERT
                                                          Y. Kadobayashi
                                                                   NAIST
                                                            Jan 14, 2014

        IODEF-extension for structured cybersecurity information
                       draft-ietf-mile-sci-13.txt

Abstract

   This document extends the Incident Object Description Exchange Format
   (IODEF) defined in RFC 5070 [RFC5070] to exchange enriched
   cybersecurity information among security experts at organizations and
   facilitates their operations.  It provides a well-defined pattern to
   consistently embed structured information, such as identifier- and
   XML-based information.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on July 18, 2014.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of

Takahashi, et al.         Expires July 18, 2014                 [Page 1]
Internet-Draft                  IODEF-SCI                       Jan 2014

   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Applicability  . . . . . . . . . . . . . . . . . . . . . . . .  4
   4.  Extension Definition . . . . . . . . . . . . . . . . . . . . .  5
     4.1.  IANA Table for Structured Cybersecurity Information  . . .  5
     4.2.  Extended Data Type: XMLDATA  . . . . . . . . . . . . . . .  6
     4.3.  Extending IODEF  . . . . . . . . . . . . . . . . . . . . .  6
     4.4.  Basic Structure of the Extension Classes . . . . . . . . .  7
     4.5.  Defining Extension Classes . . . . . . . . . . . . . . . .  9
       4.5.1.  AttackPattern  . . . . . . . . . . . . . . . . . . . .  9
       4.5.2.  Platform . . . . . . . . . . . . . . . . . . . . . . . 10
       4.5.3.  Vulnerability  . . . . . . . . . . . . . . . . . . . . 10
       4.5.4.  Scoring  . . . . . . . . . . . . . . . . . . . . . . . 11
       4.5.5.  Weakness . . . . . . . . . . . . . . . . . . . . . . . 12
       4.5.6.  EventReport  . . . . . . . . . . . . . . . . . . . . . 13
       4.5.7.  Verification . . . . . . . . . . . . . . . . . . . . . 14
       4.5.8.  Remediation  . . . . . . . . . . . . . . . . . . . . . 15
   5.  Mandatory to Implement features  . . . . . . . . . . . . . . . 15
     5.1.  An Example XML . . . . . . . . . . . . . . . . . . . . . . 16
     5.2.  An XML Schema for the Extension  . . . . . . . . . . . . . 18
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 22
     6.1.  Transport-Specific Concerns  . . . . . . . . . . . . . . . 22
     6.2.  Protection of Sensitive and Private Information  . . . . . 23
     6.3.  Application and Server Security  . . . . . . . . . . . . . 24
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 24
   8.  Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . 26
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 26
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 26
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 27
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29

Takahashi, et al.         Expires July 18, 2014                 [Page 2]
Internet-Draft                  IODEF-SCI                       Jan 2014

1.  Introduction

   The number of incidents in cyber society is growing day by day.
   Incident information needs to be reported, exchanged, and shared
   among organizations in order to cope with the situation.  IODEF is
   one of the tools already in use that enables such an exchange.

   To more efficiently run security operations, information exchanged
   between organizations needs to be machine readable.  IODEF provides a
   means to describe the incident information, but it often needs to
   include various non-structured types of incident-related data in
   order to convey more specific details about what is occurring.
   Further structure within IODEF increases the machine-readability of
   the document thus providing a means for better automating certain
   security operations.

   Within the security community there exist various means for
   specifying structured descriptions of cybersecurity information such
   as [CAPEC][CCE][CCSS][CEE][CPE][CVE][CVRF][CVSS][CWE][CWSS][MAEC]
   [OCIL][OVAL][SCAP][XCCDF].  In this context, cybersecurity
   information encompasses a broad range of structured data
   representation types that may be used to assess or report on the
   security posture of an asset or set of assets.  Such structured
   descriptions facilitates a better understanding of an incident while
   enabling more streamlined automated security operations.  Because of
   this, it would be beneficial to embed and convey these types of
   information inside IODEF documents.

   This document extends IODEF to embed and convey various types of
   structured information.  Since IODEF defines a flexible and
   extensible format and supports a granular level of specificity, this
   document defines an extension to IODEF instead of defining a new
   report format.  For clarity, and to eliminate duplication, only the
   additional structures necessary for describing the exchange of such
   structured information are provided.

2.  Terminology

   The terminology used in this document follows the one defined in RFC
   5070 [RFC5070].

   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 RFC 2119 [RFC2119].

Takahashi, et al.         Expires July 18, 2014                 [Page 3]
Internet-Draft                  IODEF-SCI                       Jan 2014

3.  Applicability

   To maintain awareness of the continually changing security threat
   landscape, organization needs to exchange cybersecurity information,
   which includes the following information: attack pattern, platform
   information, vulnerability and weakness, countermeasure instruction,
   computer event logs, and severity assessments.  IODEF provides a
   scheme to describe and exchange such information among interested
   parties.  However, it does not define the detailed formats to specify
   such information.

   There already exists structured and detailed formats for describing
   these types of information that can be used in facilitating such an
   exchange.  They include [CAPEC][CCE][CCSS][CEE][CPE]
   [CVE][CVRF][CVSS][CWE][CWSS][MAEC][OCIL][OVAL][SCAP][XCCDF].  By
   embedding them into the IODEF document, the document can convey more
   detailed context information to the receivers, and the document can
   be easily reused.

   The use of structured information formats facilitates more advanced
   security operations on the receiver side.  Since the information is
   machine readable, the data can be processed by computers thus
   allowing better automation of security operations.

   For instance, an organization wishing to report a security incident
   wants to describe what vulnerability was exploited.  In this case the
   sender can simply use IODEF, where an XML-based [XML1.0] attack
   pattern record that follows the syntax and vocabulary defined by an
   industry specification is embedded, instead of describing everything
   in free form text.  The receiver can identify the needed details of
   the attack pattern by looking up some of the XML tags defined by the
   specification.  The receiver can accumulate the attack pattern record
   in its database and could distribute it to the interested parties as
   needed, all without requiring human interventions.

   In another example, an administrator is investigating an incident and
   detected a configuration problem that he wishes to share with a
   partner organization to prevent the same event from occurring.  He
   accesses configuration information in an internal repository that was
   gathered prior to the initial attack specific to a new vulnerability
   alert to confirm the configuration was in fact vulnerable.  He uses
   this information to automatically generate an XML-based software
   configuration description, embed it in an IODEF document, and send
   the resulting IODEF document to the partner organization.

Takahashi, et al.         Expires July 18, 2014                 [Page 4]
Internet-Draft                  IODEF-SCI                       Jan 2014

4.  Extension Definition

   This document extends IODEF to embed structured information by
   introducing new classes that can be embedded consistently inside an
   IODEF document as element contents of the AdditionalData and
   RecordItem classes.

4.1.  IANA Table for Structured Cybersecurity Information

   This extension embeds structured cybersecurity information defined by
   other specifications.  The list of supported specifications is
   managed by IANA, and this document defines the needed fields for the
   list's entry.

   Each entry has namespace [XMLNames], specification name, version,
   reference URI, and applicable classes for each specification.
   Arbitrary URIs that may help readers to understand the specification
   could be embedded inside the Reference URI field, but it is
   recommended that standard/informational URI describing the
   specification is prepared and is embedded here.

   The initial IANA table has only one entry, as below.

     Namespace:          urn:ietf:params:xml:ns:mile:mmdef:1.2
     Specification Name: Malware Metadata Exchange Format
     Version:            1.2
     Reference URI:      http://standards.ieee.org/develop
                         /indconn/icsg/mmdef.html,
                         http://grouper.ieee.org/groups
                         /malware/malwg/Schema1.2/
     Applicable Classes: AttackPattern

   Note that the specification was developed by The Institute of
   Electrical and Electronics Engineers, Incorporated (IEEE), through
   the Industry Connections Security Group (ICSG) of its Standards
   Association.

   The table is to be managed by IANA following the allocation policy
   specified in Section 7.

   The SpecID attributes of extension classes (Section 4.5) must allow
   the values of the specifications' namespace fields, but otherwise,
   implementations are not required to support all specifications of the
   IANA table and may choose which specifications to support, though the
   specification listed in the initial table needs to be minimally
   supported, as described in Section 5.  In case an implementation

Takahashi, et al.         Expires July 18, 2014                 [Page 5]
Internet-Draft                  IODEF-SCI                       Jan 2014

   received a data it does not support, it may expand its functionality
   by looking up the IANA table or notify the sender of its inability to
   parse the data.  Note that the look-up could be done manually or
   automatically, but automatic download of data from IANA's website is
   not recommended since it is not designed for mass retrieval of data
   by multiple devices.

4.2.  Extended Data Type: XMLDATA

   This extension inherits all of the data types defined in the IODEF
   data model.  One data type is added: XMLDATA.  An embedded XML data
   is represented by the XMLDATA data type.  This type is defined as the
   extension to the iodef:ExtensionType [RFC5070], whose dtype attribute
   is set to "xml".

4.3.  Extending IODEF

   This document defines eight extension classes, namely AttackPattern,
   Platform, Vulnerability, Scoring, Weakness, EventReport, Verification
   and Remediation.  Figure 1 describes the relationships between the
   IODEF Incident class [RFC5070] and the newly defined classes.  It is
   expressed in Unified Modeling Language (UML) syntax as with the RFC
   5070 [RFC5070].  The UML representation is for illustrative purposes
   only; elements are specified in XML as defined in Section 5.2.

Takahashi, et al.         Expires July 18, 2014                 [Page 6]
Internet-Draft                  IODEF-SCI                       Jan 2014

+---------------+
| Incident      |
+---------------+
| ENUM purpose  |<>---------[IncidentID]
| STRING        |<>--{0..1}-[AlternativeID]
|   ext-purpose |<>--{0..1}-[RelatedActivity]
| ENUM lang     |<>--{0..1}-[DetectTime]
| ENUM          |<>--{0..1}-[StartTime]
|   restriction |<>--{0..1}-[EndTime]
|               |<>---------[ReportTime]
|               |<>--{0..*}-[Description]
|               |<>--{1..*}-[Assessment]
|               |<>--{0..*}-[Method]
|               |            |<>--{0..*}-[AdditionalData]
|               |                  |<>--{0..*}-[AttackPattern]
|               |                  |<>--{0..*}-[Vulnerability]
|               |                  |<>--{0..*}-[Weakness]
|               |<>--{1..*}-[Contact]
|               |<>--{0..*}-[EventData]
|               |            |<>--{0..*}-[Flow]
|               |            |     |<>--{1..*}-[System]
|               |            |           |<>--{0..*}-[AdditionalData]
|               |            |                 |<>--{0..*}-[Platform]
|               |            |<>--{0..*}-[Expectation]
|               |            |<>--{0..1}-[Record]
|               |                  |<>--{1..*}-[RecordData]
|               |                        |<>--{1..*}-[RecordItem]
|               |                              |<>--{0..*}-[EventReport]
|               |<>--{0..1}-[History]
|               |<>--{0..*}-[AdditionalData]
|               |            |<>--{0..*}-[Verification]
|               |            |<>--{0..*}-[Remediation]
+---------------+

                         Figure 1: Incident class

4.4.  Basic Structure of the Extension Classes

   Figure 2 shows the basic structure of the extension classes.  Some of
   the extension classes have extra elements as defined in Section 4.5,
   but the basic structure is the same.

Takahashi, et al.         Expires July 18, 2014                 [Page 7]
Internet-Draft                  IODEF-SCI                       Jan 2014

   +---------------------+
   | New Class Name      |
   +---------------------+
   | ENUM SpecID         |<>--(0..*)-[ RawData ]
   | STRING ext-SpecID   |<>--(0..*)-[ Reference ]
   | STRING ContentID    |
   +---------------------+

                         Figure 2: Basic Structure

   Three attributes are defined as below.

   SpecID:  REQUIRED.  ENUM.  A specification's identifier that
      specifies the format of a structured information.  The value
      should be chosen from the namespaces [XMLNames] listed in the IANA
      table (Section 4.1) or "private".  The value "private" is prepared
      for conveying structured information based on a format that is not
      listed in the table.  This is usually used for conveying data
      formatted according to an organization's private schema.  When the
      value "private" is used, ext-SpecID element MUST be used.

   ext-SpecID:  OPTIONAL.  STRING.  A specification's identifier that
      specifies the format of a structured information.  This is usually
      used to support private schema that is not listed in the IANA
      table (Section 4.1).  This attribute MUST be used only when the
      value of SpecID element is "private."

   ContentID:  OPTIONAL.  STRING.  An identifier of a structured
      information.  Depending on the extension classes, the content of
      the structured information differs.  This attribute enables IODEF
      documents to covey the identifier of a structured information
      instead of conveying the information itself.

   Likewise, three elements are defined as below.

   RawData:  Zero or more.  XMLDATA.  An XML of a structured
      information.  This is a complete document that is formatted
      according to the specification and its version identified by the
      SpecID/ext-SpecID.  When this element is used, writers/senders
      MUST ensure that the namespace specified by SpecID/ext-SpecID and
      the schema of the XML are consistent; if not, the namespace
      identified by SpecID SHOULD be preferred, and the inconsistency
      SHOULD be logged so a human can correct the problem.

   Reference:  Zero or more of iodef:Reference [RFC5070].  A reference
      to a structured information.  This element allows an IODEF
      document to include a link to a structured information instead of
      directly embedding it into a RawData element.

Takahashi, et al.         Expires July 18, 2014                 [Page 8]
Internet-Draft                  IODEF-SCI                       Jan 2014

   Though ContentID, RawData, and Reference are optional attribute and
   elements, one of them MUST be used to convey structured information.
   Note that only one of them SHOULD be used to avoid confusing the
   receiver.

4.5.  Defining Extension Classes

   This document defines the following seven extension classes.

4.5.1.  AttackPattern

   An AttackPattern is an extension class to the
   Incident.Method.AdditionalData element with a dtype of "xml".  It
   describes attack patterns of incidents or events.  It is RECOMMENDED
   that Method class contain the extension elements whenever available.
   An AttackPattern class is structured as follows.

   +---------------------+
   | AttackPattern       |
   +---------------------+
   | ENUM SpecID         |<>--(0..*)-[ RawData ]
   | STRING ext-SpecID   |<>--(0..*)-[ Reference ]
   | STRING ContentID    |<>--(0..*)-[ Platform ]
   +---------------------+

                       Figure 3: AttackPattern class

   This class has the following attributes.

   SpecID:  REQUIRED.  ENUM.  See Section 4.4.

   ext-SpecID:  OPTIONAL.  STRING.  See Section 4.4.

   ContentID:  OPTIONAL.  STRING.  An identifier of an attack pattern
      information.  See Section 4.4.

   Likewise, this class has the following elements.

   RawData:  Zero or more.  XMLDATA.  An XML of an attack pattern
      information.  See Section 4.4.

   Reference:  Zero or more.  A reference to an attack pattern
      information.  See Section 4.4.

Takahashi, et al.         Expires July 18, 2014                 [Page 9]
Internet-Draft                  IODEF-SCI                       Jan 2014

   Platform:  Zero or more.  An identifier of software platform involved
      in the specific attack pattern.  See Section 4.5.2.

4.5.2.  Platform

   A Platform is an extension class that identifies a software platform.
   It is RECOMMENDED that AttackPattern, Vulnerability, Weakness, and
   System classes contain the extension elements whenever available.  A
   Platform element is structured as follows.

   +---------------------+
   | Platform            |
   +---------------------+
   | ENUM SpecID         |<>--(0..*)-[ RawData ]
   | STRING ext-SpecID   |<>--(0..*)-[ Reference ]
   | STRING ContentID    |
   +---------------------+

                         Figure 4: Platform class

   This class has the following attributes.

   SpecID:  REQUIRED.  ENUM.  See Section 4.4.

   ext-SpecID:  OPTIONAL.  STRING.  See Section 4.4.

   ContentID:  OPTIONAL.  STRING.  An identifier of a platform
      information.  See Section 4.4.

   Likewise, this class has the following elements.

   RawData:  Zero or more.  XMLDATA.  An XML of a platform information.
      See Section 4.4.

   Reference:  Zero or more.  A reference to a platform information.
      See Section 4.4.

4.5.3.  Vulnerability

   A Vulnerability is an extension class to the
   Incident.Method.AdditionalData element with a dtype of "xml".  The
   extension describes the vulnerabilities that are exposed or were
   exploited in incidents.  It is RECOMMENDED that Method class contain
   the extension elements whenever available.  A Vulnerability element
   is structured as follows.

Takahashi, et al.         Expires July 18, 2014                [Page 10]
Internet-Draft                  IODEF-SCI                       Jan 2014

   +---------------------+
   | Vulnerability       |
   +---------------------+
   | ENUM SpecID         |<>--(0..*)-[ RawData ]
   | STRING ext-SpecID   |<>--(0..*)-[ Reference ]
   | STRING ContentID    |<>--(0..*)-[ Platform ]
   |                     |<>--(0..*)-[ Scoring ]
   +---------------------+

                       Figure 5: Vulnerability class

   This class has the following attributes.

   SpecID:  REQUIRED.  ENUM.  See Section 4.4.

   ext-SpecID:  OPTIONAL.  STRING.  See Section 4.4.

   ContentID:  OPTIONAL.  STRING.  An identifier of a vulnerability
      information.  See Section 4.4.

   Likewise, this class has the following elements.

   RawData:  Zero or more.  XMLDATA.  An XML of a vulnerability
      information.  See Section 4.4.

   Reference:  Zero or more.  A reference to a vulnerability
      information.  See Section 4.4.

   Platform:  Zero or more.  An identifier of software platform affected
      by the vulnerability.  See Section 4.5.2.

   Scoring:  Zero or more.  An indicator of the severity of the
      vulnerability.  See Section 4.5.4.

4.5.4.  Scoring

   A Scoring is an extension class that describes the severity scores in
   terms of security.  It is RECOMMENDED that Vulnerability and Weakness
   classes contain the extension elements whenever available.  A Scoring
   class is structured as follows.

Takahashi, et al.         Expires July 18, 2014                [Page 11]
Internet-Draft                  IODEF-SCI                       Jan 2014

   +---------------------+
   | Scoring             |
   +---------------------+
   | ENUM SpecID         |<>--(0..*)-[ RawData ]
   | STRING ext-SpecID   |<>--(0..*)-[ Reference ]
   | STRING ContentID    |
   +---------------------+

                          Figure 6: Scoring class

   This class has two attributes.

   SpecID:  REQUIRED.  ENUM.  See Section 4.4.

   ext-SpecID:  OPTIONAL.  STRING.  See Section 4.4.

   ContentID:  OPTIONAL.  STRING.  An identifier of a score set.  See
      Section 4.4.

   Likewise, this class has the following elements.

   RawData:  Zero or more.  XMLDATA.  An XML of a score set.  See
      Section 4.4.

   Reference:  Zero or more.  A reference to a score set.  See
      Section 4.4.

4.5.5.  Weakness

   A Weakness is an extension class to the
   Incident.Method.AdditionalData element with a dtype of "xml".  The
   extension describes the weakness types that are exposed or were
   exploited in incidents.  It is RECOMMENDED that Method class contain
   the extension elements whenever available.  A Weakness element is
   structured as follows.

   +---------------------+
   | Weakness            |
   +---------------------+
   | ENUM SpecID         |<>--(0..*)-[ RawData ]
   | STRING ext-SpecID   |<>--(0..*)-[ Reference ]
   | STRING ContentID    |<>--(0..*)-[ Platform ]
   |                     |<>--(0..*)-[ Scoring ]
   +---------------------+

                         Figure 7: Weakness class

Takahashi, et al.         Expires July 18, 2014                [Page 12]
Internet-Draft                  IODEF-SCI                       Jan 2014

   This class has the following attributes.

   SpecID:  REQUIRED.  ENUM.  See Section 4.4.

   ext-SpecID:  OPTIONAL.  STRING.  See Section 4.4.

   ContentID:  OPTIONAL.  STRING.  An identifier of a weakness
      information.  See Section 4.4.

   Likewise, this class has the following elements.

   RawData:  Zero or more.  XMLDATA.  An XML of a weakness information.
      See Section 4.4.

   Reference:  Zero or more.  A reference to a weakness information.
      See Section 4.4.

   Platform:  Zero or more.  An identifier of software platform affected
      by the weakness.  See Section 4.5.2.

   Scoring:  Zero or more.  An indicator of the severity of the
      weakness.  See Section 4.5.4.

4.5.6.  EventReport

   An EventReport is an extension class to the
   Incident.EventData.Record.RecordData.RecordItem element with a dtype
   of "xml".  The extension embeds structured event reports.  It is
   RECOMMENDED that RecordItem class contain the extension elements
   whenever available.  An EventReport element is structured as follows.

   +---------------------+
   | EventReport         |
   +---------------------+
   | ENUM SpecID         |<>--(0..*)-[ RawData ]
   | STRING ext-SpecID   |<>--(0..*)-[ Reference ]
   | STRING ContentID    |
   +---------------------+

                        Figure 8: EventReport class

   This class has the following attributes.

   SpecID:  REQUIRED.  ENUM.  See Section 4.4.

Takahashi, et al.         Expires July 18, 2014                [Page 13]
Internet-Draft                  IODEF-SCI                       Jan 2014

   ext-SpecID:  OPTIONAL.  STRING.  See Section 4.4.

   ContentID:  OPTIONAL.  STRING.  An identifier of an event report.
      See Section 4.4.

   Likewise, this class has the following elements.

   RawData:  Zero or more.  XMLDATA.  An XML of an event report.  See
      Section 4.4.

   Reference:  Zero or more.  A reference to an event report.  See
      Section 4.4.

4.5.7.  Verification

   A Verification is an extension class to the Incident.AdditionalData
   element with a dtype of "xml".  The extension elements describes
   information on verifying security, e.g., checklist, to cope with
   incidents.  It is RECOMMENDED that Incident class contain the
   extension elements whenever available.  A Verification class is
   structured as follows.

   +---------------------+
   | Verification        |
   +---------------------+
   | ENUM SpecID         |<>--(0..*)-[ RawData ]
   | STRING ext-SpecID   |<>--(0..*)-[ Reference ]
   | STRING ContentID    |
   +---------------------+

                       Figure 9: Verification class

   This class has the following attributes.

   SpecID:  REQUIRED.  ENUM.  See Section 4.4.

   ext-SpecID:  OPTIONAL.  STRING.  See Section 4.4.

   ContentID:  OPTIONAL.  STRING.  An identifier of a verification
      information.  See Section 4.4.

   Likewise, this class has the following elements.

   RawData:  Zero or more.  XMLDATA.  An XML of a verification
      information.  See Section 4.4.

Takahashi, et al.         Expires July 18, 2014                [Page 14]
Internet-Draft                  IODEF-SCI                       Jan 2014

   Reference:  Zero or more.  A reference to a verification information.
      See Section 4.4.

4.5.8.  Remediation

   A Remediation is an extension class to the Incident.AdditionalData
   element with a dtype of "xml".  The extension elements describes
   incident remediation information including instructions.  It is
   RECOMMENDED that Incident class contain the extension elements
   whenever available.  A Remediation class is structured as follows.

   +---------------------+
   | Remediation         |
   +---------------------+
   | ENUM SpecID         |<>--(0..*)-[ RawData ]
   | STRING ext-SpecID   |<>--(0..*)-[ Reference ]
   | String ContentID    |
   +---------------------+

                       Figure 10: Remediation class

   This class has the following attributes.

   SpecID:  REQUIRED.  ENUM.  See Section 4.4.

   ext-SpecID:  OPTIONAL.  STRING.  See Section 4.4.

   ContentID:  OPTIONAL.  STRING.  An identifier of a remediation
      information.  See Section 4.4.

   Likewise, this class has the following elements.

   RawData:  Zero or more.  XMLDATA.  An XML of a remediation
      information.  See Section 4.4.

   Reference:  Zero or more.  A reference to a remediation information.
      See Section 4.4.

5.  Mandatory to Implement features

   The implementation of this document MUST be capable of sending and
   receiving the XML conforming to the specification listed in the
   initial IANA table described in Section 4.1 without error.  An SCI
   document is an XML document that MUST be well-formed and MUST be
   valid according to schemata, including extension schemata, available
   to the validator and applicable to the XML document.  Note that the
   receiver can look up the namespace in the IANA table to understand

Takahashi, et al.         Expires July 18, 2014                [Page 15]
Internet-Draft                  IODEF-SCI                       Jan 2014

   what specifications the embedded XML documents follows.

   For the purpose of facilitating the understanding of mandatory to
   implement features, the following subsections provide an XML
   conformant to this document, and a schema for that.

5.1.  An Example XML

   An example IODEF document for checking implementation's MTI
   conformity is provided here.  The document carries MMDEF metadata.
   Note that the metadata is generated by genMMDEF [MMDEF] with EICAR
   [EICAR] files.

<?xml version="1.0" encoding="UTF-8"?>
<IODEF-Document version="1.00" lang="en"
 xmlns="urn:ietf:params:xml:ns:iodef-1.0"
 xmlns:iodef="urn:ietf:params:xml:ns:iodef-1.0"
 xmlns:iodef-sci="urn:ietf:params:xml:ns:iodef-sci-1.0"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <Incident purpose="reporting">
    <IncidentID name="iodef-sci.example.com">189493</IncidentID>
    <ReportTime>2013-06-18T23:19:24+00:00</ReportTime>
    <Description>a candidate security incident</Description>
    <Assessment>
      <Impact completion="failed" type="admin" />
    </Assessment>
    <Method>
      <Description>A candidate attack event</Description>
      <AdditionalData dtype="xml">
        <iodef-sci:AttackPattern
         SpecID="http://xml/metadataSharing.xsd">
          <iodef-sci:RawData dtype="xml">
            <malwareMetaData xmlns="http://xml/metadataSharing.xsd"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xml/metadataSharing.xsd
             file:metadataSharing.xsd" version="1.200000" id="10000">
              <company>N/A</company>
              <author>MMDEF Generation Script</author>
              <comment>Test MMDEF v1.2 file generated using genMMDEF
              </comment>
              <timestamp>2013-03-23T15:12:50.726000</timestamp>
              <objects>
                <file id="6ce6f415d8475545be5ba114f208b0ff">
                  <md5>6ce6f415d8475545be5ba114f208b0ff</md5>
                  <sha1>da39a3ee5e6b4b0d3255bfef95601890afd80709</sha1>
                  <sha256>e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca4
                          95991b7852b855</sha256>
                  <sha512>cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83

Takahashi, et al.         Expires July 18, 2014                [Page 16]
Internet-Draft                  IODEF-SCI                       Jan 2014

                          f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b9
                          31bd47417a81a538327af927da3e</sha512>
                  <size>184</size>
                  <filename>eicar_com.zip</filename>
                  <MIMEType>application/zip</MIMEType>
                </file>
                <file id="44d88612fea8a8f36de82e1278abb02f">
                  <md5>44d88612fea8a8f36de82e1278abb02f</md5>
                  <sha1>3395856ce81f2b7382dee72602f798b642f14140</sha1>
                  <sha256>275a021bbfb6489e54d471899f7db9d1663fc695ec2fe2a2c4
                          538aabf651fd0f</sha256>
                  <sha512>cc805d5fab1fd71a4ab352a9c533e65fb2d5b885518f4e565e
                          68847223b8e6b85cb48f3afad842726d99239c9e36505c64b0
                          dc9a061d9e507d833277ada336ab</sha512>
                  <size>68</size>
                  <crc32>1750191932</crc32>
                  <filename>eicar.com</filename>
                  <filenameWithinInstaller>eicar.com
                  </filenameWithinInstaller>
                </file>
              </objects>
            <relationships>
              <relationship type="createdBy" id="1">
                <source>
                  <ref>file[@id="6ce6f415d8475545be5ba114f208b0ff"]</ref>
                </source>
                <target>
                  <ref>file[@id="44d88612fea8a8f36de82e1278abb02f"]</ref>
                </target>
                <timestamp>2013-03-23T15:12:50.744000</timestamp>
                </relationship>
              </relationships>
            </malwareMetaData>
          </iodef-sci:RawData>
        </iodef-sci:AttackPattern>
      </AdditionalData>
    </Method>
    <Contact role="creator" type="organization">
      <ContactName>iodef-sci.example.com</ContactName>
      <RegistryHandle registry="arin">iodef-sci.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>

Takahashi, et al.         Expires July 18, 2014                [Page 17]
Internet-Draft                  IODEF-SCI                       Jan 2014

            <Counter type="event">57</Counter>
          </Node>
        </System>
        <System category="target">
          <Node>
            <Address category="ipv4-net">192.0.2.16/28</Address>
          </Node>
          <Service ip_protocol="4">
            <Port>80</Port>
          </Service>
        </System>
      </Flow>
      <Expectation action="block-host" />
      <Expectation action="other" />
    </EventData>
  </Incident>
</IODEF-Document>

5.2.  An XML Schema for the Extension

   An XML schema describing the elements defined in this document is
   given here.

<?xml version="1.0" encoding="UTF-8"?>

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

<xsd:import namespace="urn:ietf:params:xml:ns:iodef-1.0"
 schemaLocation="urn:ietf:params:xml:schema:iodef-1.0"/>

  <xsd:complexType name="XMLDATA">
    <xsd:complexContent>
      <xsd:restriction base="iodef:ExtensionType">
        <xsd:sequence>
          <xsd:any namespace="##any" processContents="lax" minOccurs="0"
           maxOccurs="unbounded"/>
        </xsd:sequence>
        <xsd:attribute name="dtype" type="iodef:dtype-type"
         use="required" fixed="xml"/>
        <xsd:attribute name="ext-dtype" type="xsd:string" use="optional"/>
        <xsd:attribute name="meaning" type="xsd:string"/>
        <xsd:attribute name="formatid" type="xsd:string"/>
        <xsd:attribute name="restriction" type="iodef:restriction-type"/>
      </xsd:restriction>

Takahashi, et al.         Expires July 18, 2014                [Page 18]
Internet-Draft                  IODEF-SCI                       Jan 2014

    </xsd:complexContent>
  </xsd:complexType>

  <xsd:element name="Scoring">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:choice>
          <xsd:element name="ScoreSet" type="iodef-sci:XMLDATA"
           minOccurs="0" maxOccurs="unbounded"/>
          <xsd:element ref="iodef:Reference" minOccurs="0"
           maxOccurs="unbounded"/>
        </xsd:choice>
      </xsd:sequence>
      <xsd:attribute name="SpecID" type="xsd:string" use="required"/>
      <xsd:attribute name="ext-SpecID" type="xsd:string"
       use="optional"/>
      <xsd:attribute name="ContentID" type="xsd:string"
       use="optional"/>
    </xsd:complexType>
  </xsd:element>

  <xsd:element name="AttackPattern">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:choice>
          <xsd:element name="RawData" type="iodef-sci:XMLDATA"
           minOccurs="0" maxOccurs="unbounded"/>
          <xsd:element ref="iodef:Reference" minOccurs="0"
           maxOccurs="unbounded"/>
        </xsd:choice>
        <xsd:element ref="iodef-sci:Platform" minOccurs="0"
         maxOccurs="unbounded"/>
      </xsd:sequence>
      <xsd:attribute name="SpecID" type="xsd:string" use="required"/>
      <xsd:attribute name="ext-SpecID" type="xsd:string"
       use="optional"/>
      <xsd:attribute name="ContentID" type="xsd:string"
       use="optional"/>
    </xsd:complexType>
  </xsd:element>

  <xsd:element name="Vulnerability">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:choice>
          <xsd:element name="RawData" type="iodef-sci:XMLDATA"
           minOccurs="0" maxOccurs="unbounded"/>
          <xsd:element ref="iodef:Reference" minOccurs="0"

Takahashi, et al.         Expires July 18, 2014                [Page 19]
Internet-Draft                  IODEF-SCI                       Jan 2014

           maxOccurs="unbounded"/>
        </xsd:choice>
        <xsd:element ref="iodef-sci:Platform" minOccurs="0"
         maxOccurs="unbounded"/>
        <xsd:element ref="iodef-sci:Scoring" minOccurs="0"
         maxOccurs="unbounded"/>
      </xsd:sequence>
      <xsd:attribute name="SpecID" type="xsd:string" use="required"/>
      <xsd:attribute name="ext-SpecID" type="xsd:string"
       use="optional"/>
      <xsd:attribute name="ContentID" type="xsd:string"
       use="optional"/>
    </xsd:complexType>
  </xsd:element>

  <xsd:element name="Weakness">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:choice>
          <xsd:element name="RawData" type="iodef-sci:XMLDATA"
           minOccurs="0" maxOccurs="unbounded"/>
          <xsd:element ref="iodef:Reference" minOccurs="0"
           maxOccurs="unbounded"/>
        </xsd:choice>
        <xsd:element ref="iodef-sci:Platform" minOccurs="0"
         maxOccurs="unbounded"/>
        <xsd:element ref="iodef-sci:Scoring" minOccurs="0"
         maxOccurs="unbounded"/>
      </xsd:sequence>
      <xsd:attribute name="SpecID" type="xsd:string" use="required"/>
      <xsd:attribute name="ext-SpecID" type="xsd:string"
       use="optional"/>
      <xsd:attribute name="ContentID" type="xsd:string"
       use="optional"/>
    </xsd:complexType>
  </xsd:element>

  <xsd:element name="Platform">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:choice>
          <xsd:element name="RawData" type="iodef-sci:XMLDATA"
           minOccurs="0" maxOccurs="unbounded"/>
          <xsd:element ref="iodef:Reference" minOccurs="0"
           maxOccurs="unbounded"/>
        </xsd:choice>
      </xsd:sequence>
      <xsd:attribute name="SpecID" type="xsd:string" use="required"/>

Takahashi, et al.         Expires July 18, 2014                [Page 20]
Internet-Draft                  IODEF-SCI                       Jan 2014

      <xsd:attribute name="ext-SpecID" type="xsd:string"
       use="optional"/>
      <xsd:attribute name="ContentID" type="xsd:string"
       use="optional"/>
    </xsd:complexType>
  </xsd:element>

  <xsd:element name="EventReport">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:choice>
          <xsd:element name="RawData" type="iodef-sci:XMLDATA"
           minOccurs="0" maxOccurs="unbounded"/>
          <xsd:element ref="iodef:Reference" minOccurs="0"
           maxOccurs="unbounded"/>
        </xsd:choice>
      </xsd:sequence>
      <xsd:attribute name="SpecID" type="xsd:string" use="required"/>
      <xsd:attribute name="ext-SpecID" type="xsd:string"
       use="optional"/>
      <xsd:attribute name="ContentID" type="xsd:string"
       use="optional"/>
    </xsd:complexType>
  </xsd:element>

  <xsd:element name="Verification">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:choice>
          <xsd:element name="RawData" type="iodef-sci:XMLDATA"
           minOccurs="0" maxOccurs="unbounded"/>
          <xsd:element ref="iodef:Reference" minOccurs="0"
           maxOccurs="unbounded"/>
        </xsd:choice>
      </xsd:sequence>
      <xsd:attribute name="SpecID" type="xsd:string" use="required"/>
      <xsd:attribute name="ext-SpecID" type="xsd:string"
       use="optional"/>
      <xsd:attribute name="ContentID" type="xsd:string"
       use="optional"/>
    </xsd:complexType>
  </xsd:element>

  <xsd:element name="Remediation">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:choice>
          <xsd:element name="RawData" type="iodef-sci:XMLDATA"

Takahashi, et al.         Expires July 18, 2014                [Page 21]
Internet-Draft                  IODEF-SCI                       Jan 2014

           minOccurs="0" maxOccurs="unbounded"/>
          <xsd:element ref="iodef:Reference" minOccurs="0"
           maxOccurs="unbounded"/>
        </xsd:choice>
      </xsd:sequence>
      <xsd:attribute name="SpecID" type="xsd:string" use="required"/>
      <xsd:attribute name="ext-SpecID" type="xsd:string"
       use="optional"/>
      <xsd:attribute name="ContentID" type="xsd:string"
       use="optional"/>
    </xsd:complexType>
  </xsd:element>

</xsd:schema>

6.  Security Considerations

   This document specifies a format for encoding a particular class of
   security incidents appropriate for exchange across organizations.  As
   merely a data representation, it does not directly introduce security
   issues.  However, it is guaranteed that parties exchanging instances
   of this specification will have certain concerns.  For this reason,
   the underlying message format and transport protocol used MUST ensure
   the appropriate degree of confidentiality, integrity, and
   authenticity for the specific environment.  Specific security
   considerations are detailed in the messaging and transport documents,
   where the exchange of formatted information is automated.  See Real-
   time Inter-network Defense (RID) [RFC6545] Section 9 for a detailed
   overview of security requirements and considerations.

   It is RECOMMENDED that organizations who exchange data using this
   document develop operating procedures that minimally consider the
   following areas of concern.

6.1.  Transport-Specific Concerns

   The underlying messaging format, IODEF, provides data markers to
   indicate the sensitivity level of specific classes within the
   structure as well as for the entire XML document.  The "restriction"
   attribute accomplishes this with four attribute values in IODEF.
   These values are RECOMMENDED for use at the application level, prior
   to transport, to protect data as appropriate.  A standard mechanism
   to apply XML encryption using these attribute values as triggers is
   defined in RID [RFC6545] Section 9.1.  This mechanism may be used
   whether or not the RID and RID Transport binding [RFC6546] are used
   in the exchange to provide object level security on the data to
   prevent possible intermediary systems or middle-boxes from having

Takahashi, et al.         Expires July 18, 2014                [Page 22]
Internet-Draft                  IODEF-SCI                       Jan 2014

   access to the data being exchanged.  In areas where transmission
   security or secrecy is questionable, the application of a XML digital
   signature [xmldsig] and/or encryption on each report will counteract
   both of these concerns.  The data markers are RECOMMENDED for use by
   applications for managing access controls, however access controls
   and management of those controls are out-of-scope for this document.
   Options such as the usage of a standard language (e.g.  XACML
   [XACML]) for the expression of authorization policies can be used to
   enable source and destination systems to better coordinate and align
   their respective policy expressions.

   Any transport protocol used to exchange instances of IODEF documents
   MUST provide appropriate guarantees of confidentiality, integrity,
   and authenticity.  The use of a standardized security protocol is
   encouraged.  The RID protocol [RFC6545] and its associated transport
   binding [RFC6546] provide such security with options for mutual
   authentication session encryption and include application levels
   concerns such as policy and work flow.

   The critical security concerns are that these structured information
   may be falsified, accessed by unintended entities, or they may become
   corrupt during transit.  We expect that each exchanging organization
   will determine the need, and mechanism, for transport protection.

6.2.  Protection of Sensitive and Private Information

   For a complete review of privacy considerations when transporting
   incident related information, please see RID [RFC6545] Section 9.5.
   Whether or not the RID protocol is used, the privacy considerations
   are important to consider as incident information is often sensitive
   and may contain privacy related information about individuals/
   organizations or endpoints involved.  Often times, organizations will
   require legal review and formal polices to be established which
   outline specific details of what information can be exchanged with
   specific entities.  Typically, identifying information is anonymized
   where possible and appropriate.  In some cases, information brokers
   are used to further anonymize the source of exchanged information so
   that other entities are unaware of the origin of a detected threat,
   whether or not that threat was realized.

   It is RECOMMENDED that policies and procedures for the exchange of
   cybersecurity information are established prior to participation in
   data exchanges.  Policy and workflow procedures for the exchange of
   cybersecurity information often require executive level approvals and
   legal reviews to appropriately establish limits on what information
   can be exchanged with specific organizations.  RID [RFC6545] Section
   9.6 outlines options and considerations for application developers to
   consider for the policy and workflow design.

Takahashi, et al.         Expires July 18, 2014                [Page 23]
Internet-Draft                  IODEF-SCI                       Jan 2014

6.3.  Application and Server Security

   The Cybersecurity Information extension is merely a data format.
   Applications and transport protocols that store or exchange IODEF
   documents using information that can be represented through this
   extension will be a target for attacks.  It is RECOMMENDED that
   systems and applications storing or exchanging this information are
   properly secured, have minimal services enabled, maintain access
   controls and monitoring procedures.

7.  IANA Considerations

   This document uses URNs to describe XML namespaces and XML schemata
   [XMLschemaPart1] [XMLschemaPart2] conforming to a registry mechanism
   described in [RFC3688].

   Registration request for the IODEF structured cybersecurity
   information extension namespace:

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

      Registrant Contact: Refer here to the authors' addresses section
      of the document.

      XML: None.

   Registration request for the IODEF structured cybersecurity
   information extension XML schema:

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

      Registrant Contact: Refer here to the authors' addresses section
      of the document.

      XML: Refer here to the XML Schema in Section 5.2.

   This memo creates the following registry for IANA to manage:

      Name of the registry: "Structured Cybersecurity Information (SCI)
      specifications"

      Name of its parent registry: "Incident Object Description Exchange
      Format (IODEF)"

      URL address of the registry: http://www.iana.org/assignments/iodef

Takahashi, et al.         Expires July 18, 2014                [Page 24]
Internet-Draft                  IODEF-SCI                       Jan 2014

      Namespace details: A registry entry for a Structured Cybersecurity
      Information Specification (SCI specification) consists of:

         Namespace: A URI [RFC3986] that identifies the XML namespace
         used by the registered SCI specification.  In the case where
         the registrant does not request a particular URI, the IANA will
         assign it a Uniform Resource Name (URN) that follows RFC 3553
         [RFC3553]

         Specification Name: A string containing the spelled-out name of
         the SCI specification in human-readable form.

         Reference URI: A list of one or more of the URIs [RFC3986] from
         which the registered specification can be obtained.  The
         registered specification MUST be readily and publicly available
         from that URI.

         Applicable Classes: A list of one or more of the extension
         classes specified in Section 4.5 of this document.  The
         registered SCI specification MUST only be used with the
         extension classes in the registry entry.

      Information that must be provided to assign a new value: The above
      list of information.

      Fields to record in the registry: Namespace/Specification Name/
      Version/Reference URI/Applicable Classes.  Note that it is not
      necessary to include defining reference for all assignments in
      this new registry.

      Initial registry contents: only one entry with the following
      values.

         Namespace: urn:ietf:params:xml:ns:mile:mmdef:1.0

         Specification Name: Malware Metadata Exchange Format

         Version: 1.2

         Reference URI: http://standards.ieee.org/develop/indconn/icsg/
         mmdef.html,http://grouper.ieee.org/groups/malware/malwg/
         Schema1.2/

         Applicable Classes: AttackPattern

      Allocation Policy: Specification Required (which includes Expert
      Review) [RFC5226].

Takahashi, et al.         Expires July 18, 2014                [Page 25]
Internet-Draft                  IODEF-SCI                       Jan 2014

   The Designated Expert is expected to consult with the mile (Managed
   Incident Lightweight Exchange) working group or its successor if any
   such WG exists (e.g., via email to the working group's mailing list).
   The Designated Expert is expected to retrieve the SCI specification
   from the provided URI in order to check the public availability of
   the specification and verify the correctness of the URI.  An
   important responsibility of the Designated Expert is to ensure that
   the registered Applicable Classes are appropriate for the registered
   SCI specification.

8.  Acknowledgment

   We would like to acknowledge David Black from EMC, who kindly
   provided generous support, especially on the IANA registry issues.
   We also would like to thank Jon Baker from MITRE, Eric Burger from
   Georgetown University, Paul Cichonski from NIST, Panos Kampanakis
   from CISCO, Pearl Liang from IANA, Ivan Kirillov from MITRE, Robert
   Martin from MITRE, Alexey Melnikov from Isode, Kathleen Moriarty from
   EMC, Lagadec Philippe from NATO, Sean Turner from IECA Inc., Shuhei
   Yamaguchi from NICT, Anthony Rutkowski from Yaana Technology, Brian
   Trammell from ETH Zurich, David Waltermire from NIST, and James
   Wendorf from IEEE, for their sincere discussion and feedback on this
   document.

9.  References

9.1.  Normative References

   [MMDEF]    IEEE ICSG Malware Metadata Exchange Format Working Group,
              "Malware Metadata Exchange Format".

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

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [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.

Takahashi, et al.         Expires July 18, 2014                [Page 26]
Internet-Draft                  IODEF-SCI                       Jan 2014

   [RFC6545]  Moriarty, K., "Real-time Inter-network Defense (RID)",
              RFC 6545, April 2012.

   [RFC6546]  Trammell, B., "Transport of Real-time Inter-network
              Defense (RID) Messages over HTTP/TLS", RFC 6546,
              April 2012.

   [XML1.0]   Bray, T., Maler, E., Paoli, J., Sperberg-McQueen, C., and
              F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
              Edition)", W3C Recommendation, November 2008.

   [XMLschemaPart1]
              Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn,
              "XML Schema Part 1: Structures Second Edition",
              W3C Recommendation, October 2004.

   [XMLschemaPart2]
              Biron, P. and A. Malhotra, "XML Schema Part 2: Datatypes
              Second Edition", W3C Recommendation, October 2004.

   [XMLNames]
              Bray, T., Hollander, D., Layman, A., Tobin, R., and H.
              Thomson, ""Namespaces in XML (Third Edition)",
              W3C Recommendation, December 2009.

9.2.  Informative References

   [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.

   [RFC3553]  Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An
              IETF URN Sub-namespace for Registered Protocol
              Parameters", BCP 73, RFC 3553, June 2003.

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

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

   [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.

Takahashi, et al.         Expires July 18, 2014                [Page 27]
Internet-Draft                  IODEF-SCI                       Jan 2014

   [CAPEC]    The MITRE Corporation, "Common Attack Pattern Enumeration
              and Classification (CAPEC)".

   [CCE]      The MITRE Corporation, "Common Configuration Enumeration
              (CCE)".

   [CCSS]     Scarfone, K. and P. Mell, "The Common Configuration
              Scoring System (CCSS)", NIST Interagency Report 7502,
              December 2010.

   [CEE]      The MITRE Corporation, "Common Event Expression (CEE)".

   [CPE]      National Institute of Standards and Technology, "Common
              Platform Enumeration", June 2011.

   [CVE]      The MITRE Corporation, "Common Vulnerability and Exposures
              (CVE)".

   [CVRF]     ICASI, "Common Vulnerability Reporting Framework (CVRF)".

   [CVSS]     Peter Mell, Karen Scarfone, and Sasha Romanosky, "The
              Common Vulnerability Scoring System (CVSS) and Its
              Applicability to Federal Agency Systems".

   [CWE]      The MITRE Corporation, "Common Weakness Enumeration
              (CWE)".

   [CWSS]     The MITRE Corporation, "Common Weakness Scoring System
              (CWSS)".

   [EICAR]    European Expert Group for IT-Security, "Anti-Malware
              Testfile", 2003.

   [MAEC]     The MITRE Corporation, "Malware Attribute Enumeration and
              Characterization".

   [OCIL]     David Waltermire and Karen Scarfone and Maria Casipe, "The
              Open Checklist Interactive Language (OCIL) Version 2.0",
              April 2011.

   [OVAL]     The MITRE Corporation, "Open Vulnerability and Assessment
              Language (OVAL)".

   [SCAP]     Waltermire, D., Quinn, S., Scarfone, K., and A.
              Halbardier, "The Technical Specification for the Security
              Content Automation Protocol (SCAP): SCAP Version 1.2",
              NIST Special Publication 800-126 Revision 2,
              September 2011.

Takahashi, et al.         Expires July 18, 2014                [Page 28]
Internet-Draft                  IODEF-SCI                       Jan 2014

   [XACML]    Rissanen, E., "eXtensible Access Control Markup Language
              (XACML) Version 3.0", January 2013, <http://
              docs.oasis-open.org/xacml/3.0/
              xacml-3.0-core-spec-os-en.pdf>.

   [XCCDF]    David Waltermire and Charles Schmidt and Karen Scarfone
              and Neal Ziring, "Specification for the Extensible
              Configuration Checklist Description Format (XCCDF) version
              1.2 (DRAFT)", July 2011.

   [xmldsig]  W3C Recommendation, "XML Signature Syntax and Processing
              (Second Edition)", June 2008.

Authors' Addresses

   Takeshi Takahashi
   National Institute of Information and Communications Technology
   4-2-1 Nukui-Kitamachi Koganei
   184-8795 Tokyo
   Japan

   Phone: +80 423 27 5862
   Email: takeshi_takahashi@nict.go.jp

   Kent Landfield
   McAfee, Inc
   5000 Headquarters Drive
   Plano, TX 75024
   USA

   Email: Kent_Landfield@McAfee.com

   Thomas Millar
   US Department of Homeland Security, NPPD/CS&C/NCSD/US-CERT
   245 Murray Lane SW, Building 410, MS #732
   Washington, DC 20598
   USA

   Phone: +1 888 282 0870
   Email: thomas.millar@us-cert.gov

Takahashi, et al.         Expires July 18, 2014                [Page 29]
Internet-Draft                  IODEF-SCI                       Jan 2014

   Youki Kadobayashi
   Nara Institute of Science and Technology
   8916-5 Takayama, Ikoma
   630-0192 Nara
   Japan

   Email: youki-k@is.aist-nara.ac.jp

Takahashi, et al.         Expires July 18, 2014                [Page 30]