Discovering and Retrieving Software Transparency and Vulnerability Information
draft-ietf-opsawg-sbom-access-05

Network Working Group                                            E. Lear
Internet-Draft                                             Cisco Systems
Intended status: Standards Track                                 S. Rose
Expires: 7 September 2022                                           NIST
                                                            6 March 2022

   Discovering and Retrieving Software Transparency and Vulnerability
                              Information
                    draft-ietf-opsawg-sbom-access-05

Abstract

   To improve cybersecurity posture, automation is necessary to locate
   what software is running on a device, whether that software has known
   vulnerabilities, and what, if any recommendations suppliers may have.
   This memo specifies a model to provide access to this information.
   It may optionally be discovered through manufacturer usage
   descriptions.

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 https://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 7 September 2022.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  How This Information Is Retrieved . . . . . . . . . . . .   5
     1.2.  Formats . . . . . . . . . . . . . . . . . . . . . . . . .   5
     1.3.  Discussion points . . . . . . . . . . . . . . . . . . . .   5
   2.  The well-known transparency endpoint set  . . . . . . . . . .   6
   3.  The mud-transparency extension model extension  . . . . . . .   6
   4.  The mud-sbom augmentation to the MUD YANG model . . . . . . .   6
   5.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  10
     5.1.  Without ACLS  . . . . . . . . . . . . . . . . . . . . . .  10
     5.2.  SBOM Located on the Device  . . . . . . . . . . . . . . .  12
     5.3.  Further contact required. . . . . . . . . . . . . . . . .  13
     5.4.  With ACLS . . . . . . . . . . . . . . . . . . . . . . . .  14
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
     7.1.  MUD Extension . . . . . . . . . . . . . . . . . . . . . .  18
     7.2.  YANG Registration . . . . . . . . . . . . . . . . . . . .  18
     7.3.  Well-Known Prefix . . . . . . . . . . . . . . . . . . . .  18
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  19
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  19
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  19
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  20
   Appendix A.  Changes from Earlier Versions  . . . . . . . . . . .  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  21

1.  Introduction

   A number of activities have been working to improve visibility to
   what software is running on a system, and what vulnerabilities that
   software may have[EO2021].

   Put simply, we seek to answer two classes of questions *at scale*:

   *  Is this system vulnerable to a particular vulnerability?

   *  Which devices in a particular environment contain vulnerabilities
      that require some action?

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   This memo doesn't specify the format of this information, but rather
   only how to locate and retrieve these objects.

   Software bills of materials (SBOMs) are descriptions of what
   software, including versioning and dependencies, a device contains.
   There are different SBOM formats such as Software Package Data
   Exchange [SPDX] or CycloneDX[CycloneDX12].

   System vulnerabilities may similarly be described using several data
   formats, including the aforementioned CycloneDX, Common Vulnerability
   Reporting Framework [CVRF], the Common Security Advisory Format
   [CSAF].  This information is typically used to report to customers
   the state of a system.

   These two classes of information can be used in concert.  For
   instance, a network management tool may discover that a system makes
   use of a particular software component that has a known
   vulnerability, and a vulnerability report may be used to indicate
   what if any versions of software correct that vulnerability, or
   whether the system exercises the vulnerable code at all.

   Both classes of information elements are optional under the model
   specified in this memo.  One can provide only an SBOM, only
   vulnerability information, or both an SBOM and vulnerability
   information.

   Note that SBOM formats may also carry other information, the most
   common being any licensing terms.  Because this specification is
   neutral regarding content, it is left for format developers such as
   the Linux Foundation, OASIS, and ISO to decide what attributes they
   will support.

   This memo does not specify how vulnerability information may be
   retrieved directly from the endpoint.  That's because vulnerability
   information changes occur at different rates to software updates.
   However, some SBOM formats may also contain vulnerability
   information.

   SBOMs and vulnerability information are advertised and retrieved
   through the use of a YANG augmentation of the Manufacturer User
   Description (MUD) model [RFC8520].  Note that the schema creates a
   grouping that can also be used independently of MUD.  Moreover, other
   MUD features, such as access controls, needn't be present.

   The mechanisms specified in this document are meant to satisfy
   several use cases:

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   *  A network-layer management system retrieving information from an
      IoT device as part of its ongoing lifecycle.  Such devices may or
      may not have query interfaces available.

   *  An application-layer management system retrieving vulnerability or
      SBOM information in order to evaluate the posture of an
      application server of some form.  These application servers may
      themselves be containers or hypervisors.  Discovery of the
      topology of a server is beyond the scope of this memo.

   To satisfy these two key use cases, objects may be found in one of
   three ways:

   *  on devices themselves

   *  on a web site (e.g., via URI)

   *  through some form of out-of-band contact with the supplier.

   In the first case, devices will have interfaces that permit direct
   retrieval.  Examples of these interfaces might be an HTTP, COAP or
   [OpenC2] endpoint for retrieval.  There may also be private
   interfaces as well.

   In the second case, when a device does not have an appropriate
   retrieval interface, but one is directly available from the
   manufacturer, a URI to that information MUST be discovered.

   In the third case, a supplier may wish to make an SBOM or
   vulnerability information available under certain circumstances, and
   may need to individually evaluate requests.  The result of that
   evaluation might be the SBOM or vulnerability itself or a restricted
   URL or no access.

   To enable application-layer discovery, this memo defines a well-known
   URI [RFC8615].  Management or orchestration tools can query this
   well-known URI to retrieve a system's SBOM or vulnerability
   information.  Further queries may be necessary based on the content
   and structure of the response.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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1.1.  How This Information Is Retrieved

   For devices that can emit a URL or can establish a well-known URI,
   the mechanism may be highly automated.  For devices that have a URL
   in either their documentation or within a QR code on a box, the
   mechanism is semi-automated (someone has to scan the QR code or enter
   the URL).

   Note that vulnerability and SBOM information is likely to change at
   different rates.  The MUD semantics provide a way for manufacturers
   to control how often tooling should check for those changes through
   the cache-validity node.

1.2.  Formats

   There are multiple ways to express both SBOMs and vulnerability
   information.  When these are retrieved either directly from the
   device or directly from a web server, tools will need to observe the
   content-type header to determine precisely which format is being
   transmitted.  Because IoT devices in particular have limited
   capabilities, use of a specific Accept: header in HTTP or the Accept
   Option in CoAP is NOT RECOMMENDED.  Instead, backend tooling is
   encouraged to support all known formats, and SHOULD silently discard
   SBOM information sent with a media type that is not understood.

   Some formats may support both vulnerability and software inventory
   information.  When both vulnerability and software inventory
   information is available from the same location, both sbom and vuln
   nodes MUST indicate that.  Network management systems retrieving this
   information MUST take note that the identical resource is being
   retrieved rather than retrieving it twice.

1.3.  Discussion points

   The following is discussion to be removed at time of RFC publication.

   *  Is the model structured correctly?

   *  Are there other retrieval mechanisms that need to be specified?

   *  Do we need to be more specific in how to authenticate and retrieve
      SBOMs?

   *  What are the implications if the MUD URL is an extension in a
      certificate (e.g. an IDevID cert)?

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2.  The well-known transparency endpoint set

   Two well known endpoints are defined:

   *  "/.well-known/sbom" retrieves an SBOM.

   *  "/.well-known/openc2" is the HTTPS binding to OpenC2.

   As discussed previously, the precise format of a response is based on
   the Content-type provided.

3.  The mud-transparency extension model extension

   We now formally define this extension.  This is done in two parts.
   First, the extension name "transparency" is listed in the
   "extensions" array of the MUD file.  N.B., this schema extension is
   intended to be used wherever it might be appropriate (e.g., not just
   MUD).

   Second, the "mud" container is augmented with a list of SBOM sources.

   This is done as follows:

   module: ietf-mud-transparency

     augment /mud:mud:
       +--rw transparency
          +--rw (sbom-retrieval-method)?
          |  +--:(cloud)
          |  |  +--rw sboms* [version-info]
          |  |     +--rw version-info    string
          |  |     +--rw sbom-url?       inet:uri
          |  +--:(local-well-known)
          |  |  +--rw sbom-local-well-known?   enumeration
          |  +--:(sbom-contact-info)
          |     +--rw sbom-contact-uri         inet:uri
          +--rw (vuln-retrieval-method)?
             +--:(cloud)
             |  +--rw vuln-url?                inet:uri
             +--:(vuln-contact-info)
                +--rw contact-uri              inet:uri

4.  The mud-sbom augmentation to the MUD YANG model

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   <CODE BEGINS>
   file "ietf-mud-transparency@2021-10-22.yang"
   module ietf-mud-transparency {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-mud-transparency";
     prefix mudtx;

     import ietf-inet-types {
       prefix inet;
       reference "RFC 6991";
   }
     import ietf-mud {
       prefix mud;
       reference "RFC 8520";
     }

     organization
       "IETF OPSAWG (Ops Area) Working Group";
     contact
       "WG Web: http://tools.ietf.org/wg/opsawg/
        WG List: opsawg@ietf.org

        Editor: Eliot Lear lear@cisco.com
        Editor: Scott Rose scott.rose@nist.gov";
     description
       "This YANG module augments the ietf-mud model to provide for
        reporting of SBOMs and vulnerability information.

        Copyright (c) 2020 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject to
        the license terms contained in, the Simplified BSD License set
        forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX);
        see the RFC itself for full legal notices.

        The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
        NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
        'MAY', and 'OPTIONAL' in this document are to be interpreted as
        described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
        they appear in all capitals, as shown here.  ";

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     revision 2021-07-06 {
       description
         "Initial proposed standard.";
       reference
         "RFC XXXX: Discovering and Retrieving Software Transparency
          and Vulnerability Information";
     }

     grouping transparency-extension {
       description
         "Transparency extension grouping";
       container transparency {
         description
           "container of methods to get an SBOM.";
         choice sbom-retrieval-method {
           description
             "How to find SBOM information";
           case cloud {
             list sboms {
               key "version-info";
               description
                 "A list of SBOMs tied to different s/w
                  or h/w versions.";
               leaf version-info {
                 type string;
                 description
                   "The version to which this SBOM refers.";
               }
               leaf sbom-url {
                 type inet:uri;
                 description
                   "A statically located URI.";
               }
             }
           }
           case local-well-known {
             leaf sbom-local-well-known {
               type enumeration {
                 enum http {
                   description
                     "Use http (insecure) to retrieve
                      SBOM information.  This method is NOT RECOMMENDED,
                      but may be unavoidable for certain classes of
                      deployment, where TLS has not or cannot be implemented";
                 }
                 enum https {
                   description
                     "Use https (secure) to retrieve SBOM information.";

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                 }
                 enum coap {
                   description
                     "Use COAP (insecure) to retrieve SBOM.  This method
                     is NOT RECOMMENDED, although it may be unavoidable
                     for certain classes of implementations/deployments.";
                 }
                 enum coaps {
                   description
                     "Use COAPS (secure) to retrieve SBOM";
                 }
                 enum openc2 {
                   description
                     "Use OpenC2 endpoint.
                      This is https://{host}/.well-known/openc2";
                 }
               }
               description
                 "Which communication protocol to choose.";
             }
           }
           case sbom-contact-info {
             leaf sbom-contact-uri {
               type inet:uri;
               mandatory true;
               description
                 "This MUST be either a tel, http, https, or
                  mailto uri schema that customers can use to
                  contact someone for SBOM information.";
             }
           }
         }
         choice vuln-retrieval-method {
           description
             "How to find vulnerability information";
           case cloud {
             leaf vuln-url {
               type inet:uri;
               description
                 "A statically located URL.";
             }
           }
           case vuln-contact-info {
             leaf contact-uri {
               type inet:uri;
               mandatory true;
               description
                 "This MUST be either a tel, http, https, or

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                  mailto uri schema that customers can use to
                  contact someone for vulnerability information.";
             }
           }
         }
       }
     }

     augment "/mud:mud" {
       description
         "Add extension for software transparency.";
       uses transparency-extension;
     }
   }
   <CODE ENDS>

5.  Examples

   In this example MUD file that uses a cloud service, the modelX
   presents a location of the SBOM in a URL.  Note, the ACLs in a MUD
   file are NOT required, although they are a very good idea for IP-
   based devices.

5.1.  Without ACLS

   This first MUD file demonstrates how to get SBOM and vulnerability
   information without ACLs.

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  {
    "ietf-mud:mud": {
      "mud-version": 1,
      "extensions": [
        "ol",
        "transparency"
      ],
      "ol": {
        "owners": [
          "Copyright (c) Example, Inc. 2022. All Rights Reserved"
        ],
        "spdx-tag": "0BSD"
      },
      "mudtx:transparency": {
        "sbom-local-well-known": "https",
        "vuln-url": "https://iot.example.com/info/modelX/csaf.json"
      },
      "mud-url": "https://iot.example.com/modelX.json",
      "mud-signature": "https://iot.example.com/modelX.p7s",
      "last-update": "2022-01-05T13:29:12+00:00",
      "cache-validity": 48,
      "is-supported": true,
      "systeminfo": "retrieving vuln and SBOM info via a cloud service",
      "mfg-name": "Example, Inc.",
      "documentation": "https://iot.example.com/doc/modelX",
      "model-name": "modelX"
    }
  }

   The second example demonstrates that just SBOM information is
   included.

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  {
    "ietf-mud:mud": {
      "mud-version": 1,
      "extensions": [
        "ol",
        "transparency"
      ],
      "ol": {
        "owners": [
          "Copyright (c) Example, Inc. 2022. All Rights Reserved"
        ],
        "spdx-tag": "0BSD"
      },
      "mudtx:transparency": {
        "sbom-local-well-known": "https"
      },
      "mud-url": "https://iot.example.com/modelX.json",
      "mud-signature": "https://iot.example.com/modelX.p7s",
      "last-update": "2022-01-05T13:29:47+00:00",
      "cache-validity": 48,
      "is-supported": true,
      "systeminfo": "retrieving vuln and SBOM info via a cloud service",
      "mfg-name": "Example, Inc.",
      "documentation": "https://iot.example.com/doc/modelX",
      "model-name": "modelX"
    }
  }

5.2.  SBOM Located on the Device

   In this example, the SBOM is retrieved from the device, while
   vulnerability information is available from the cloud.  This is
   likely a common case, because vendors may learn of vulnerability
   information more frequently than they update software.

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{
  "ietf-mud:mud": {
    "mud-version": 1,
    "extensions": [
      "transparency"
    ],
    "mudtx:transparency": {
      "sbom-local-well-known": "https",
      "vuln-url": "https://iot-device.example.com/info/modelX/csaf.json"
    },
    "mud-url": "https://iot-device.example.com/modelX.json",
    "mud-signature": "https://iot-device.example.com/modelX.p7s",
    "last-update": "2022-01-05T13:25:14+00:00",
    "cache-validity": 48,
    "is-supported": true,
    "systeminfo": "retrieving vuln and SBOM info via a cloud service",
    "mfg-name": "Example, Inc.",
    "documentation": "https://iot-device.example.com/doc/modelX",
    "model-name": "modelX"
  }
}

5.3.  Further contact required.

   In this example, the network manager must take further steps to
   retrieve SBOM information.  Vulnerability information is still
   available.

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 {
  "ietf-mud:mud": {
   "mud-version": 1,
   "extensions": [
     "transparency"
   ],
   "ietf-mud-transparency:transparency": {
     "contact-info": "https://iot-device.example.com/contact-info.html",
     "vuln-url": "https://iot-device.example.com/info/modelX/csaf.json"
   },
   "mud-url": "https://iot-device.example.com/modelX.json",
   "mud-signature": "https://iot-device.example.com/modelX.p7s",
   "last-update": "2021-07-09T06:16:42+00:00",
   "cache-validity": 48,
   "is-supported": true,
   "systeminfo": "retrieving vuln and SBOM info via a cloud service",
   "mfg-name": "Example, Inc.",
   "documentation": "https://iot-device.example.com/doc/modelX",
   "model-name": "modelX"
  }
 }

5.4.  With ACLS

   Finally, here is a complete example where the device provides SBOM
   and vulnerability information, as well as access-control information.

  {
    "ietf-mud:mud": {
      "mud-version": 1,
      "extensions": [
        "ol",
        "transparency"
      ],
      "ol": {
        "owners": [
          "Copyright (c) Example, Inc. 2022. All Rights Reserved"
        ],
        "spdx-tag": "0BSD"
      },
      "mudtx:transparency": {
        "sbom-local-well-known": "https",
        "vuln-url": "https://iot.example.com/info/modelX/csaf.json"
      },
      "mud-url": "https://iot.example.com/modelX.json",
      "mud-signature": "https://iot.example.com/modelX.p7s",
      "last-update": "2022-01-05T13:30:31+00:00",
      "cache-validity": 48,

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      "is-supported": true,
      "systeminfo": "retrieving vuln and SBOM info via a cloud service",
      "mfg-name": "Example, Inc.",
      "documentation": "https://iot.example.com/doc/modelX",
      "model-name": "modelX",
      "from-device-policy": {
        "access-lists": {
          "access-list": [
            {
              "name": "mud-65443-v4fr"
            }
          ]
        }
      },
      "to-device-policy": {
        "access-lists": {
          "access-list": [
            {
              "name": "mud-65443-v4to"
            }
          ]
        }
      }
    },
    "ietf-access-control-list:acls": {
      "acl": [
        {
          "name": "mud-65443-v4to",
          "type": "ipv4-acl-type",
          "aces": {
            "ace": [
              {
                "name": "cl0-todev",
                "matches": {
                  "ipv4": {
                    "ietf-acldns:src-dnsname": "iotserver.example.com"
                  }
                },
                "actions": {
                  "forwarding": "accept"
                }
              }
            ]
          }
        },
        {
          "name": "mud-65443-v4fr",
          "type": "ipv4-acl-type",

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          "aces": {
            "ace": [
              {
                "name": "cl0-frdev",
                "matches": {
                  "ipv4": {
                    "ietf-acldns:dst-dnsname": "iotserver.example.com"
                  }
                },
                "actions": {
                  "forwarding": "accept"
                }
              }
            ]
          }
        }
      ]
    }
  }

   At this point, the management system can attempt to retrieve the
   SBOM, and determine which format is in use through the content-type
   header on the response to a GET request, independently repeat the
   process for vulnerability information, and apply ACLs, as
   appropriate.

6.  Security Considerations

   The YANG module specified in this document defines a schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC8446].

   N.B., for MUD, the mandatory method of retrieval is TLS.

   The Network Configuration Access Control Model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to a preconfigured subset of all available NETCONF or
   RESTCONF protocol operations and content.

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   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  These are the subtrees and data nodes
   and their sensitivity/vulnerability:

   The ietf-mud-transparency module has no operational impact on the
   element itself, and is used to discover state information that may be
   available on or off the element.  In as much as the module itself is
   made writeable, this only indicates a change in how to retrieve what
   read-only elements.  However, that does not mean there are no risks.
   These are discussed below, and are applicable to all nodes within the
   transparency container.

   If an attacker modifies the elements, they may misdirect automation
   to retrieve a different set of URLs than was intended by the
   designer.  This in turn leads to two specific sets of risks:

   *  the information retrieved would be false.

   *  the URLs themselves point to malware.

   To address either risk, any change in a URL, and in particular to the
   authority section, should be treated with some suspicion.  One
   mitigation would be to test any cloud-based URL against a reputation
   service.

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These are the subtrees and data
   nodes and their sensitivity/vulnerability:

   SBOMs provide an inventory of software.  If software is available to
   an attacker, the attacker may well already be able to derive this
   very same software inventory.  Manufacturers MAY restrict access to
   SBOM information using appropriate authorization semantics within
   HTTP.  In particular, if a system attempts to retrieve an SBOM via
   HTTP and the client is not authorized, the server MUST produce an
   appropriate error, with instructions on how to register a particular
   client.  One example may be to issue a certificate to the client for
   this purpose after a registration process has taken place.  Another
   example would involve the use of OAUTH in combination with a
   federations of SBOM servers.

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   Another risk is a skew in the SBOM listing and the actual software
   inventory of a device/container.  For example, a manufacturer may
   update the SBOM on its server, but an individual device has not been
   upgraded yet.  This may result in an incorrect policy being applied
   to a device.  A unique mapping of a device's software version and its
   SBOM can minimize this risk.

   To further mitigate attacks against a device, manufacturers SHOULD
   recommend access controls.

   Vulnerability information is generally made available to such
   databases as NIST's National Vulnerability Database.  It is possible
   that vendor may wish to release information early to some customers.
   We do not discuss here whether that is a good idea, but if it is
   employed, then appropriate access controls and authorization SHOULD
   be applied to the vulnerability resource.

7.  IANA Considerations

7.1.  MUD Extension

   The IANA is requested to add "transparency" to the MUD extensions
   registry as follows:

     Extension Name: transparency
     Standard reference: This document

7.2.  YANG Registration

   The following YANG module should be registered in the "YANG Module
   Names" registry:

      Name: ietf-mud
      URN: urn:ietf:params:xml:ns:yang:ietf-mud-transparency
      Prefix: mudtx
      Registrant contact: The IESG
      Reference: This memo

7.3.  Well-Known Prefix

   The following well known URIs are requested in accordance with
   [RFC8615]:

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     URI suffix: "sbom"
     Change controller: "IETF"
     Specification document: This memo
     Related information:  See ISO/IEC 19970-2 and SPDX.org

     URI suffix: "openc2"
     Change controller: "IETF"
     Specification document: This memo
     Related information:  OpenC2 Project

8.  Acknowledgments

   Thanks to Russ Housley, Dick Brooks, Tom Petch, Nicolas Comstedt, who
   provided revew comments.

9.  References

9.1.  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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

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   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC8520]  Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage
              Description Specification", RFC 8520,
              DOI 10.17487/RFC8520, March 2019,
              <https://www.rfc-editor.org/info/rfc8520>.

   [RFC8615]  Nottingham, M., "Well-Known Uniform Resource Identifiers
              (URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019,
              <https://www.rfc-editor.org/info/rfc8615>.

9.2.  Informative References

   [CSAF]     OASIS, "Common Security Advisory Format", July 2021,
              <https://github.com/oasis-tcs/csaf>.

   [CVRF]     Santos, O., Ed., "Common Vulnerability Reporting Framework
              (CVRF) Version 1.2", September 2017, <https://docs.oasis-
              open.org/csaf/csaf-cvrf/v1.2/csaf-cvrf-v1.2.pdf>.

   [CycloneDX12]
              cylonedx.org, "CycloneDX XML Reference v1.2", May 2020.

   [EO2021]   Biden, J., "Executive Order 14028, Improving the Nations
              Cybersecurity", May 2021.

   [OpenC2]   Lemire, D., Ed., "Specification for Transfer of OpenC2
              Messages via HTTPS Version 1.0", July 2019,
              <https://docs.oasis-open.org/openc2/open-impl-https/v1.0/
              open-impl-https-v1.0.html>.

   [SPDX]     The Linux Foundation, "SPDX Specification 2.1", 2016.

Appendix A.  Changes from Earlier Versions

   Draft -04: * Address review comments

   Draft -02:

   *  include vulnerability information

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   Draft -01:

   *  some modest changes

   Draft -00:

   *  Initial revision

Authors' Addresses

   Eliot Lear
   Cisco Systems
   Richtistrasse 7
   CH-8304 Wallisellen
   Switzerland
   Phone: +41 44 878 9200
   Email: lear@cisco.com

   Scott Rose
   NIST
   100 Bureau Dr
   Gaithersburg MD,  20899
   United States of America
   Phone: +1 301-975-8439
   Email: scott.rose@nist.gov

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