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OVAL(R) Directives Model
draft-rothenberg-sacm-oval-directives-model-00

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Authors Michael Cokus , Daniel Haynes , David Rothenberg , Juan Gonzalez
Last updated 2016-03-07
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draft-rothenberg-sacm-oval-directives-model-00
Security Automation and Continuous Monitoring                   M. Cokus
Internet-Draft                                                 D. Haynes
Intended status: Informational                             D. Rothenberg
Expires: September 8, 2016                         The MITRE Corporation
                                                             J. Gonzalez
                                         Department of Homeland Security
                                                           March 7, 2016

                        OVAL(R) Directives Model
             draft-rothenberg-sacm-oval-directives-model-00

Abstract

   This document specifies Version 5.11.1 of the OVAL Directives Model
   which defines the constructs used to tailor the level of detail
   contained within a set of OVAL Results.

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 September 8, 2016.

Copyright Notice

   Copyright (c) 2016 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
   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

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  OVAL Directives Model . . . . . . . . . . . . . . . . . . . .   3
   3.  OVAL Directives Model Schema  . . . . . . . . . . . . . . . .   4
   4.  Intellectual Property Considerations  . . . . . . . . . . . .   8
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   The Open Vulnerability and Assessment Language (OVAL) [OVAL-WEBSITE]
   is an international, information security community effort to
   standardize how to assess and report upon the machine state of
   systems.  For over ten years, OVAL has been developed in
   collaboration with any and all interested parties to promote open and
   publicly available security content and to standardize the
   representation of this information across the entire spectrum of
   security tools and services.

   OVAL provides an established framework for making assertions about a
   system's state by standardizing the three main steps of the
   assessment process: representing the current machine state; analyzing
   the system for the presence of the specified machine state; and
   representing the results of the assessment which facilitates
   collaboration and information sharing among the information security
   community and interoperability among tools.

   This draft is the part of the OVAL contribution to the IETF SACM WG
   that standardizes the representation of the results of an assessment.
   It is intended to serve as a starting point for the endpoint posture
   assessment data modeling needs of SACM specifically a capability to
   specify the level of detail in Evaluation Results.

1.1.  Requirements Language

   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].

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2.  OVAL Directives Model

   The OVAL Directives Model is used to control what result information
   is included in the OVAL Results as well as specify its level of
   detail.

   +---------------+---------------------------+-------+---------------+
   | Property      | Type                      | Count | Description   |
   +---------------+---------------------------+-------+---------------+
   | generator     | oval:GeneratorType        | 1     | Information   |
   |               |                           |       | regarding the |
   |               |                           |       | generation of |
   |               |                           |       | the OVAL      |
   |               |                           |       | Directives    |
   |               |                           |       | content. The  |
   |               |                           |       | timestamp     |
   |               |                           |       | property of   |
   |               |                           |       | the generator |
   |               |                           |       | MUST          |
   |               |                           |       | represent the |
   |               |                           |       | time at which |
   |               |                           |       | the oval_dire |
   |               |                           |       | ctives was    |
   |               |                           |       | created.      |
   |               |                           |       |               |
   | directives    | oval-                     | 1     | Describes the |
   |               | res:DefaultDirectivesType |       | default set   |
   |               |                           |       | of directives |
   |               |                           |       | that specify  |
   |               |                           |       | the results   |
   |               |                           |       | that have     |
   |               |                           |       | been included |
   |               |                           |       | in the OVAL   |
   |               |                           |       | Results.      |
   |               |                           |       |               |
   | class_directi | oval-                     | 0..5  | Describes the |
   | ves           | res:ClassDirectivesType   |       | set of        |
   |               |                           |       | directives    |
   |               |                           |       | that specify  |
   |               |                           |       | the class-    |
   |               |                           |       | specific      |
   |               |                           |       | results that  |
   |               |                           |       | have been     |
   |               |                           |       | included in   |
   |               |                           |       | the OVAL      |
   |               |                           |       | Results.      |
   |               |                           |       |               |
   | signature     | ext:Signature             | 0..1  | Mechanism to  |

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   |               |                           |       | ensure the    |
   |               |                           |       | integrity and |
   |               |                           |       | authenticity  |
   |               |                           |       | of the OVAL   |
   |               |                           |       | Directives    |
   |               |                           |       | content.      |
   +---------------+---------------------------+-------+---------------+

                    Table 1: oval_directives Construct

3.  OVAL Directives Model Schema

   The XML Schema that implements this OVAL Directives Model can be
   found below.

           <?xml version="1.0" encoding="utf-8"?>
   <xsd:schema
        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
        xmlns:oval="http://oval.mitre.org/XMLSchema/oval-common-5"
        xmlns:oval-res=
        "http://oval.mitre.org/XMLSchema/oval-results-5"
        xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
        xmlns:sch="http://purl.oclc.org/dsdl/schematron"
        xmlns:oval-dir=
        "http://oval.mitre.org/XMLSchema/oval-directives-5"
        targetNamespace=
        "http://oval.mitre.org/XMLSchema/oval-directives-5"
        elementFormDefault="qualified" version="5.11">
        <xsd:import namespace=
             "http://oval.mitre.org/XMLSchema/oval-common-5"
             schemaLocation="oval-common-schema.xsd"/>
        <xsd:import namespace=
             "http://oval.mitre.org/XMLSchema/oval-results-5"
             schemaLocation="oval-results-schema.xsd"/>
        <xsd:import
             namespace="http://www.w3.org/2000/09/xmldsig#"
             schemaLocation="xmldsig-core-schema.xsd"/>
        <xsd:annotation>
             <xsd:documentation>The following is a
                  description of the elements, types,
                  and attributes that compose the
                  core schema for encoding Open
                  Vulnerability and Assessment
                  Language (OVAL) Directives. Each of
                  the elements, types, and attributes
                  that make up the Core Directives
                  Schema are described in detail and

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                  should provide the information
                  necessary to understand what each
                  object represents. This document is
                  intended for developers and assumes
                  some familiarity with XML. A high
                  level description of the
                  interaction between these objects
                  is not outlined
                  here.</xsd:documentation>
             <xsd:appinfo>
                  <schema>Core Directives</schema>
                  <version>5.11.1</version>
                  <date>4/22/2015 09:00:00 AM</date>
                  <terms_of_use>Copyright (C) 2010 United States
                    Government. All Rights Reserved.</terms_of_use>
                  <sch:ns prefix="oval-dir" uri=
                   "http://oval.mitre.org/XMLSchema/
                   oval-directives-5"
                  />
             </xsd:appinfo>
        </xsd:annotation>
        <!-- ================================================== -->
        <!-- ================================================== -->
        <!-- ================================================== -->
        <xsd:element name="oval_directives">
             <xsd:annotation>
                  <xsd:documentation>The
                       oval_directives element is the
                       root of an OVAL Directive
                       Document. Its purpose is to
                       bind together the generator
                       and the set of directives
                       contained in the document. The
                       generator section must be
                       present and provides
                       information about when the
                       directives document was
                       compiled and under what
                       version. The optional
                       Signature element allows an
                       XML Signature as defined by
                       the W3C to be attached to the
                       document. This allows
                       authentication and data
                       integrity to be provided to
                       the user. Enveloped signatures
                       are supported. More
                       information about the official

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                       W3C Recommendation regarding
                       XML digital signatures can be
                       found at
                       http://www.w3.org/TR/xmldsig-core/.
                  </xsd:documentation>
             </xsd:annotation>
             <xsd:complexType>
                  <xsd:sequence>
                       <xsd:element name="generator"
                            type="oval:GeneratorType">
                            <xsd:annotation>
                            <xsd:documentation>The
                            required generator
                            section provides
                            information about when
                            the directives document
                            was compiled and under
                            what
                            version.</xsd:documentation>
                            </xsd:annotation>
                       </xsd:element>
                       <xsd:element name="directives"
                            type="oval-res:DefaultDirectivesType">
                            <xsd:annotation>
                            <xsd:documentation>The
                            required directives
                            section presents flags
                            describing what
                            information must be been
                            included in an oval
                            results document. This
                            element represents the
                            default set of
                            directives. These
                            directives apply to all
                            classes of definitions
                            for which there is not a
                            class specific set of
                            directives.</xsd:documentation>
                            </xsd:annotation>
                       </xsd:element>
                       <xsd:element
                            name="class_directives"
                            type="oval-res:ClassDirectivesType"
                            minOccurs="0"
                            maxOccurs="5">
                            <xsd:annotation>
                            <xsd:documentation>The

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                            optional class_directives
                            section presents flags
                            describing what
                            information has been
                            included in the results
                            document for a specific
                            OVAL Definition class.
                            The directives for a
                            particlar class override
                            the default
                            directives.</xsd:documentation>
                            </xsd:annotation>
                       </xsd:element>
                       <xsd:element
                            ref="ds:Signature"
                            minOccurs="0"
                            maxOccurs="1">
                            <xsd:annotation>
                            <xsd:documentation>The
                            optional Signature
                            element allows an XML
                            Signature as defined by
                            the W3C to be attached to
                            the document. This allows
                            authentication and data
                            integrity to be provided
                            to the user. Enveloped
                            signatures are supported.
                            More information about
                            the official W3C
                            Recommendation regarding
                            XML digital signatures
                            can be found at
                            http://www.w3.org/TR/xmldsig-core/.
                            </xsd:documentation>
                            </xsd:annotation>
                       </xsd:element>
                  </xsd:sequence>
             </xsd:complexType>
             <xsd:unique name="UniqueDirectiveClass">
                  <xsd:annotation>
                       <xsd:documentation>The class
                            attribute on
                            class_directives must be
                            unique.</xsd:documentation>
                  </xsd:annotation>
                  <xsd:selector
                       xpath="oval-dir:class_directives"/>

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                  <xsd:field xpath="@class"/>
             </xsd:unique>
        </xsd:element>

        <!-- ================================================== -->
        <!-- ===================  GENERATOR  ================== -->
        <!-- ================================================== -->
        <!--
             The GeneratorType is defined by the
             oval-common-schema. Please refer to that
             documentation for a description of the complex type.
        -->
        <!-- ================================================== -->
        <!-- =================  DIRECTIVES  =================== -->
        <!-- ================================================== -->
        <!--
             The DefaultDirectivesType is defined by the
             oval-results-schema.  Please refer to that
             documentation for a description of the complex type.
        -->
        <!-- ================================================== -->
        <!-- ================  DIRECTIVES  ==================== -->
        <!-- ================================================== -->
        <!--
             The ClassDirectivesType is defined by the
             oval-results-schema.  Please refer to that
             documentation for a description of the complex type.
        -->
   </xsd:schema>

4.  Intellectual Property Considerations

   Copyright (C) 2010 United States Government.  All Rights Reserved.

   DHS, on behalf of the United States, owns the registered OVAL
   trademarks, identifying the OVAL STANDARDS SUITE and any component
   part, as that suite has been provided to the IETF Trust.  A "(R)"
   will be used in conjunction with the first use of any OVAL trademark
   in any document or publication in recognition of DHS's trademark
   ownership.

5.  Acknowledgements

   The authors wish to thank DHS for sponsoring the OVAL effort over the
   years which has made this work possible.  The authors also wish to
   thank the original authors of this document Jonathan Baker, Matthew

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   Hansbury, and Daniel Haynes of the MITRE Corporation as well as the
   OVAL Community for its assistance in contributing and reviewing the
   original document.  The authors would also like to acknowledge Dave
   Waltermire of NIST for his contribution to the development of the
   original document.

6.  IANA Considerations

   This memo includes no request to IANA.

7.  Security Considerations

   While OVAL is just a set of data models and does not directly
   introduce security concerns, it does provide a mechanism by which to
   represent endpoint posture assessment information.  This information
   could be extremely valuable to an attacker allowing them to learn
   about very sensitive information including, but, not limited to:
   security policies, systems on the network, criticality of systems,
   software and hardware inventory, patch levels, user accounts and much
   more.  To address this concern, all endpoint posture assessment
   information should be protected while in transit and at rest.
   Furthermore, it should only be shared with parties that are
   authorized to receive it.

   Another possible security concern is due to the fact that content
   expressed as OVAL has the ability to impact how a security tool
   operates.  For example, content may instruct a tool to collect
   certain information off a system or may be used to drive follow-up
   actions like remediation.  As a result, it is important for security
   tools to ensure that they are obtaining OVAL content from a trusted
   source, that it has not been modified in transit, and that proper
   validation is performed in order to ensure it does not contain
   malicious data.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

8.2.  Informative References

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   [OVAL-WEBSITE]
              The MITRE Corporation, "The Open Vulnerability and
              Assessment Language", 2015,
              <http://ovalproject.github.io/>.

Authors' Addresses

   Michael Cokus
   The MITRE Corporation
   903 Enterprise Parkway, Suite 200
   Hampton, VA  23666
   USA

   Email: msc@mitre.org

   Daniel Haynes
   The MITRE Corporation
   202 Burlington Road
   Bedford, MA  01730
   USA

   Email: dhaynes@mitre.org

   David Rothenberg
   The MITRE Corporation
   202 Burlington Road
   Bedford, MA  01730
   USA

   Email: drothenberg@mitre.org

   Juan Gonzalez
   Department of Homeland Security
   245 Murray Lane
   Washington, DC  20548
   USA

   Email: juan.gonzalez@dhs.gov

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