rfc9472.original   rfc9472.txt 
Network Working Group E. Lear Internet Engineering Task Force (IETF) E. Lear
Internet-Draft Cisco Systems Request for Comments: 9472 Cisco Systems
Intended status: Standards Track S. Rose Category: Standards Track S. Rose
Expires: 30 October 2023 NIST ISSN: 2070-1721 NIST
28 April 2023 October 2023
Discovering and Retrieving Software Transparency and Vulnerability A YANG Data Model for Reporting Software Bills of Materials (SBOMs) and
Information Vulnerability Information
draft-ietf-opsawg-sbom-access-18
Abstract Abstract
To improve cybersecurity posture, automation is necessary to locate To improve cybersecurity posture, automation is necessary to locate
the software a device is using, and whether that software has known the software a device is using, whether that software has known
vulnerabilities, and what, if any recommendations suppliers may have. vulnerabilities, and what, if any, recommendations suppliers may
This memo extends the MUD YANG schema to provide the locations of have. This memo extends the Manufacturer User Description (MUD) YANG
software bills of materials (SBOMS) and to vulnerability information schema to provide the locations of software bills of materials
by introducing a transparency schema. (SBOMs) and vulnerability information by introducing a transparency
schema.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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 This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 30 October 2023. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9472.
Copyright Notice Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents
license-info) in effect on the date of publication of this document. (https://trustee.ietf.org/license-info) in effect on the date of
Please review these documents carefully, as they describe your rights publication of this document. Please review these documents
and restrictions with respect to this document. Code Components carefully, as they describe your rights and restrictions with respect
extracted from this document must include Revised BSD License text as to this document. Code Components extracted from this document must
described in Section 4.e of the Trust Legal Provisions and are include Revised BSD License text as described in Section 4.e of the
provided without warranty as described in the Revised BSD License. Trust Legal Provisions and are provided without warranty as described
in the Revised BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
1.1. How This Information Is Retrieved . . . . . . . . . . . . 5 1.1. Requirements Language
1.2. Formats . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2. How This Information is Retrieved
2. The well-known transparency endpoint set . . . . . . . . . . 6 1.3. Formats
3. The mud-transparency extension model extension . . . . . . . 6 2. The Well-Known Transparency Endpoint Set
4. The mud-sbom augmentation to the MUD YANG model . . . . . . . 6 3. The mud-transparency Extension
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4. The mud-sbom Augmentation to the MUD YANG Data Model
5.1. Without ACLS . . . . . . . . . . . . . . . . . . . . . . 11 5. Examples
5.2. SBOM Located on the Device . . . . . . . . . . . . . . . 12 5.1. Without ACLS
5.3. Further contact required. . . . . . . . . . . . . . . . . 13 5.2. SBOM Located on the Device
5.4. With ACLS . . . . . . . . . . . . . . . . . . . . . . . . 14 5.3. Further Contact Required
6. Security Considerations . . . . . . . . . . . . . . . . . . . 16 5.4. With ACLS
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 6. Security Considerations
7.1. MUD Extension . . . . . . . . . . . . . . . . . . . . . . 18 7. IANA Considerations
7.2. YANG Registration . . . . . . . . . . . . . . . . . . . . 18 7.1. MUD Extension
7.3. Well-Known Prefix . . . . . . . . . . . . . . . . . . . . 18 7.2. YANG Registration
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19 7.3. Well-Known Prefix
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 8. References
9.1. Normative References . . . . . . . . . . . . . . . . . . 19 8.1. Normative References
9.2. Informative References . . . . . . . . . . . . . . . . . 20 8.2. Informative References
Appendix A. Changes from Earlier Versions . . . . . . . . . . . 20 Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses
1. Introduction 1. Introduction
A number of activities have been working to improve visibility to A number of activities have taken place to improve the visibility of
what software is running on a system, and what vulnerabilities that what software is running on a system and what vulnerabilities that
software may have [EO2021]. software may have [EO2021].
Put simply, this memo seeks to answer two classes of questions to the Put simply, this memo seeks to answer two classes of questions for
scale of tens of thousands of devices and a large variety of types of tens of thousands of devices and a large variety of device types.
devices. Those questions are as the following: Those questions are as follows:
* Is this system vulnerable to a particular vulnerability? * Is this system susceptible to a particular vulnerability?
* Which devices in a particular environment contain vulnerabilities * Which devices in a particular environment contain vulnerabilities
that require some action? that require some action?
This memo doesn't specify the format of this information, but rather This memo doesn't specify the format of this information but rather
only how to locate and retrieve these objects. That is, the model is only how to locate and retrieve these objects. That is, the model is
intended to facilitate discovery, and on its own provides no access intended to facilitate discovery and on its own provides no access to
to the underlying data. the underlying data.
Software bills of materials (SBOMs) are descriptions of what Software bills of materials (SBOMs) are descriptions of what
software, including versioning and dependencies, a device contains. software, including versioning and dependencies, a device contains.
There are different SBOM formats such as Software Package Data There are different SBOM formats such as Software Package Data
Exchange [SPDX] or CycloneDX[CycloneDX12]. Exchange [SPDX] or CycloneDX [CycloneDX15].
System vulnerabilities may similarly be described using several data System vulnerabilities may be similarly described using several data
formats, including the aforementioned CycloneDX, Common Vulnerability formats, including the aforementioned CycloneDX, the Common
Reporting Framework [CVRF], the Common Security Advisory Format Vulnerability Reporting Framework [CVRF], and the Common Security
[CSAF]. This information is typically used to report to Advisory Format [CSAF]. This information is typically used to report
administrators the state of any known vulnerabilities on a system. the state of any known vulnerabilities on a system to administrators.
SBOM and vulnerability information can be used in concert with other SBOM and vulnerability information can be used in concert with other
sources of vulnerability information. For a network management tool sources of vulnerability information. A network management tool
could discover that a system makes use of a particular set of could discover that a system uses a particular set of software
software components, searches a national vulnerability database to components, searches a national vulnerability database to determine
determine known vulnerabilities, and then applies information known vulnerabilities, and applies information provided by the
provided the manufacturer through this mechanism to produce a manufacturer through this mechanism to produce a vulnerability
vulnerability report. That report may be used to indicate what if report. That report may be used to indicate what, if any, versions
any versions of software correct that vulnerability, or whether the of software correct that vulnerability or whether the system
system exercises the vulnerable code at all. exercises the vulnerable code at all.
Both classes of information elements are optional under the model Both classes of information elements are optional under the model
specified in this memo. One can provide only an SBOM, only specified in this memo. One can provide only an SBOM, only
vulnerability information, or both an SBOM and vulnerability vulnerability information, or both an SBOM and vulnerability
information. information.
Note that SBOM formats may also carry other information, the most Note that SBOM formats may also carry other information, the most
common being any licensing terms. Because this specification is common being any licensing terms. Because this specification is
neutral regarding content, it is left for format developers such as neutral regarding content, it is left for format developers such as
the Linux Foundation, OASIS, and ISO to decide what attributes they the Linux Foundation, OASIS, and ISO to decide what attributes they
will support. will support.
This memo does not specify how vulnerability information may be This memo does not specify how vulnerability information may be
retrieved directly from the endpoint. That's because vulnerability retrieved directly from the endpoint. That is because vulnerability
information changes occur at different rates to software updates. information changes occur to software updates at different rates.
However, some SBOM formats may also contain vulnerability However, some SBOM formats may also contain vulnerability
information. information.
SBOMs and vulnerability information are advertised and retrieved SBOMs and vulnerability information are advertised and retrieved
through the use of a YANG augmentation of the Manufacturer User through the use of a YANG augmentation of the Manufacturer User
Description (MUD) model [RFC8520]. Note that the schema creates a Description (MUD) model [RFC8520]. Note that the schema creates a
grouping that can also be used independently of MUD. Moreover, other grouping that can also be used independently of MUD. Moreover, other
MUD features, such as access controls, needn't be present. MUD features, such as access controls, needn't be present.
The mechanisms specified in this document are meant to address two The mechanisms specified in this document are meant to address two
use cases: use cases:
* A network-layer management system retrieving information from an * A network-layer management system retrieving information from an
IoT device as part of its ongoing lifecycle. Such devices may or Internet of Things (IoT) device as part of its ongoing life cycle.
may not have query interfaces available. Such devices may or may not have query interfaces available.
* An application-layer management system retrieving vulnerability or * An application-layer management system retrieving vulnerability or
SBOM information in order to evaluate the posture of an SBOM information in order to evaluate the posture of an
application server of some form. These application servers may application server of some form. These application servers may
themselves be containers or hypervisors. Discovery of the themselves be containers or hypervisors. Discovery of the
topology of a server is beyond the scope of this memo. 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 To satisfy these two key use cases, objects may be found in one of
three methods: three methods:
* on devices themselves 1. on the devices themselves
* on a website (e.g., via URI) 2. on a website (e.g., via a URI)
* through some form of out-of-band contact with the supplier. 3. through some form of out-of-band contact with the supplier
Using the first method, devices will have interfaces that permit Using the first method, devices will have interfaces that permit
direct retrieval. Examples of these interfaces might be an HTTP direct retrieval. Examples of these interfaces might be an HTTP
[RFC9110], or COAP [RFC7252] endpoint for retrieval. There may also [RFC9110] or Constrained Application Protocol (CoAP) [RFC7252]
be private interfaces as well. endpoint for retrieval. There may also be private interfaces as
well.
Using the second method, when a device does not have an appropriate Using the second method, when a device does not have an appropriate
retrieval interface, but one is directly available from the retrieval interface, but one is directly available from the
manufacturer, a URI to that information is discovered through manufacturer, a URI to that information is discovered through
interfaces such as MUD via DHCP or bootstrapping and ownership interfaces such as MUD via DHCP or bootstrapping and ownership
transfer mechanisms. transfer mechanisms.
Using the third method, a supplier may wish to make an SBOM or Using the third method, a supplier may wish to make an SBOM or
vulnerability information available under certain circumstances, and vulnerability information available under certain circumstances and
may need to individually evaluate requests. The result of that may need to individually evaluate requests. The result of that
evaluation might be the SBOM or vulnerability itself or a restricted evaluation might be the SBOM, the vulnerability itself, a restricted
URL or no access. URL, or no access.
To enable application-layer discovery, this memo defines a well-known To enable application-layer discovery, this memo defines a well-known
URI [RFC8615]. Management or orchestration tools can query this URI [RFC8615]. Management or orchestration tools can query this
well-known URI to retrieve a system's SBOM information. Further well-known URI to retrieve a system's SBOM information. Further
queries may be necessary based on the content and structure of the queries may be necessary based on the content and structure of the
response. response.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
1.1. How This Information Is Retrieved 1.2. How This Information is Retrieved
Section 4 describes a data model to extend the MUD file format to Section 4 describes a data model to extend the MUD file format to
carry SBOM and vulnerability information. Section 1.5 of RFC8520 carry SBOM and vulnerability information. Section 1.5 of [RFC8520]
describes mechanisms by which devices can emit a URL to point to this describes mechanisms by which devices can emit a URL to point to this
file. Additionally, devices can share this URL either through file. Additionally, devices can share this URL either through
documentation or within a QR code on a box. Section 2 describes a documentation or within a QR code on a box. Section 2 describes a
well-known URL from which an SBOM could be served from the local well-known URL from which an SBOM could be served from the local
device. device.
Note that vulnerability and SBOM information are likely to change at Note that vulnerability and SBOM information are likely to change at
different rates. MUD's cache-validity node provides a way for different rates. MUD's cache-validity node provides a way for
manufacturers to control how often tooling should check for those manufacturers to control how often tooling should check for those
changes through the cache-validity node. changes through the cache-validity node.
1.2. Formats 1.3. Formats
There are multiple ways to express both SBOMs and vulnerability There are multiple ways to express both SBOMs and vulnerability
information. When these are retrieved either from the device or from information. When these are retrieved either from the device or from
a remote web server, tools will need to observe the Content-Type a remote web server, tools will need to observe the Content-Type
header to determine precisely which format is being transmitted. header to determine precisely which format is being transmitted.
Because IoT devices in particular have limited capabilities, use of a Because IoT devices in particular have limited capabilities, use of a
specific Accept: header in HTTP or the Accept Option in CoAP is NOT specific Accept: header in HTTP or the Accept Option in CoAP is NOT
RECOMMENDED. Instead, backend tooling is encouraged to support all RECOMMENDED. Instead, backend tooling is encouraged to support all
known formats, and SHOULD silently discard SBOM information sent with known formats and SHOULD silently discard SBOM information sent with
a media type that is not understood. a media type that is not understood.
If multiple SBOMs are intended to be supported in the same file, the If multiple SBOMs are intended to be supported in the same file, the
media type should properly reflect that. For example, one might make media type should properly reflect that. For example, one might make
use of application/{someformat}+json-seq. It is left to those use of application/{someformat}+json-seq. It is left to those
supporting those formats to make the appropriate registrations in supporting those formats to make the appropriate registrations in
this case. this case.
Some formats may support both vulnerability and software inventory Some formats may support both vulnerability and software inventory
information. When both vulnerability and software inventory information. When both vulnerability and software inventory
information is available from the same URL, both sbom-url and members information is available from the same URL, both sbom-url and members
of the vuln-url list MUST indicate that. Network management systems of the vuln-url list MUST indicate that. Network management systems
retrieving this information MUST take note that the identical MUST take note of when the SBOM and vulnerability information are
resource is being retrieved rather than retrieving it twice. accessible via the same resource and not retrieve the resource a
second time.
2. The well-known transparency endpoint set 2. The Well-Known Transparency Endpoint Set
A well-known endpoint is defined: A well-known endpoint is defined:
* "/.well-known/sbom" retrieves an SBOM. "/.well-known/sbom" retrieves an SBOM
As discussed previously, the precise format of a response is based on As discussed previously, the precise format of a response is based on
the Content-type provided. the Content-Type provided.
3. The mud-transparency extension model extension 3. The mud-transparency Extension
We now formally define the mud-transparency extension; this is done
in two parts.
We now formally define this extension. This is done in two parts.
First, the extension name "transparency" is listed in the First, the extension name "transparency" is listed in the
"extensions" array of the MUD file. N.B., this schema extension is "extensions" array of the MUD file. Note that this schema extension
intended to be used wherever it might be appropriate (e.g., not just is intended to be used wherever it might be appropriate (e.g., not
MUD). just with MUD).
Second, the "mud" container is augmented with a list of SBOM sources. Second, the "mud" container is augmented with a list of SBOM sources.
This is done as follows: This is done as follows:
module: ietf-mud-transparency module: ietf-mud-transparency
augment /mud:mud: augment /mud:mud:
+--rw transparency +--rw transparency
+--rw (sbom-retrieval-method)? +--rw (sbom-retrieval-method)?
skipping to change at page 6, line 48 skipping to change at line 279
| +--rw sbom-contact-uri? inet:uri | +--rw sbom-contact-uri? inet:uri
+--rw sbom-archive-list? inet:uri +--rw sbom-archive-list? inet:uri
+--rw (vuln-retrieval-method)? +--rw (vuln-retrieval-method)?
+--:(cloud) +--:(cloud)
| +--rw vuln-url* inet:uri | +--rw vuln-url* inet:uri
+--:(vuln-contact-info) +--:(vuln-contact-info)
+--rw vuln-contact-uri? inet:uri +--rw vuln-contact-uri? inet:uri
See [RFC8340] for a description of YANG trees. See [RFC8340] for a description of YANG trees.
4. The mud-sbom augmentation to the MUD YANG model 4. The mud-sbom Augmentation to the MUD YANG Data Model
<CODE BEGINS>
file "ietf-mud-transparency@2023-01-12.yang" This YANG module references [RFC6991], [RFC7231], [RFC7252],
[RFC8520], and [RFC9110].
<CODE BEGINS> file "ietf-mud-transparency@2023-09-08.yang"
module ietf-mud-transparency { module ietf-mud-transparency {
yang-version 1.1; yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-mud-transparency"; namespace "urn:ietf:params:xml:ns:yang:ietf-mud-transparency";
prefix mudtx; prefix mudtx;
import ietf-inet-types { import ietf-inet-types {
prefix inet; prefix inet;
reference reference
"RFC 6991"; "RFC 6991: Common YANG Data Types";
} }
import ietf-mud { import ietf-mud {
prefix mud; prefix mud;
reference reference
"RFC 8520"; "RFC 8520: Manufacturer Usage Description Specification";
} }
organization organization
"IETF OPSAWG (Ops Area) Working Group"; "IETF OPSAWG (Ops Area) Working Group";
contact contact
"WG Web: https://datatracker.ietf.org/wg/opsawg/ "WG Web: <https://datatracker.ietf.org/wg/opsawg/>
WG List: opsawg@ietf.org WG List: <opsawg@ietf.org>
Editor: Eliot Lear lear@cisco.com Editor: Eliot Lear <lear@cisco.com>
Editor: Scott Rose scott.rose@nist.gov"; Editor: Scott Rose <scott.rose@nist.gov>";
description description
"This YANG module augments the ietf-mud model to provide for "This YANG module augments the ietf-mud model to provide for
reporting of SBOMs and vulnerability information. reporting of SBOMs and vulnerability information.
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.
Copyright (c) 2023 IETF Trust and the persons identified as Copyright (c) 2023 IETF Trust and the persons identified as
authors of the code. All rights reserved. authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to without modification, is permitted pursuant to, and subject to
the license terms contained in, the Revised BSD License set the license terms contained in, the Revised BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents Relating to IETF Documents
(https://trustee.ietf.org/license-info). (https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX This version of this YANG module is part of RFC 9472
(https://www.rfc-editor.org/info/rfcXXXX); (https://www.rfc-editor.org/info/rfc9472);
see the RFC itself for full legal notices. 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. ";
revision 2023-01-12 { revision 2023-09-08 {
description description
"Initial proposed standard."; "Initial proposed standard.";
reference reference
"RFC XXXX: Discovering and Retrieving Software Transparency "RFC 9472: A YANG Data Model for Reporting Software Bills
and Vulnerability Information"; of Materials (SBOMs) and Vulnerability Information";
} }
identity local-type { identity local-type {
description description
"Base identity for local-well-known choices"; "Base identity for local well-known choices.";
} }
identity http { identity http {
base mudtx:local-type; base mudtx:local-type;
description description
"Use http[RFC7231] (insecure) to retrieve SBOM information. "Use http (RFC 7231) (insecure) to retrieve SBOM information.
This method is NOT RECOMMENDED, but may be unavoidable for This method is NOT RECOMMENDED but may be unavoidable for
certain classes of deployment, where TLS has not or certain classes of deployment where TLS has not or
cannot be implemented"; cannot be implemented.";
reference
"RFC 7231: Hypertext Transfer Protocol (HTTP/1.1):
Semantics and Content";
} }
identity https { identity https {
base mudtx:local-type; base mudtx:local-type;
description description
"Use https (secure) to retrieve SBOM information. See "Use https (secure) to retrieve SBOM information. See
RFC 9110."; RFC 9110.";
reference
"RFC 9110: HTTP Semantics";
} }
identity coap { identity coap {
base mudtx:local-type; base mudtx:local-type;
description description
"Use COAP [RFC7252] (insecure) to retrieve SBOM. This method "Use COAP (RFC 7252) (insecure) to retrieve SBOM. This method
is NOT RECOMMENDED, although it may be unavoidable is NOT RECOMMENDED, although it may be unavoidable
for certain classes of implementations/deployments."; for certain classes of implementations/deployments.";
reference
"RFC 7252: The Constrained Application Protocol (CoAP)";
} }
identity coaps { identity coaps {
base mudtx:local-type; base mudtx:local-type;
description description
"Use COAPS (secure) to retrieve SBOM [RFC7252]"; "Use COAPS (secure) to retrieve SBOM (RFC 7252).";
} }
grouping transparency-extension { grouping transparency-extension {
description description
"This grouping provides a means to describe the location of "This grouping provides a means to describe the location of
software bills of material and vulnerability descriptions."; software bills of material and vulnerability descriptions.";
container transparency { container transparency {
description description
"Container of methods to get SBOMs and vulnerability "Container of methods to get SBOMs and vulnerability
information."; information.";
choice sbom-retrieval-method { choice sbom-retrieval-method {
description description
"How to find SBOM information"; "How to find SBOM information.";
case cloud { case cloud {
list sboms { list sboms {
key "version-info"; key "version-info";
description description
"A list of SBOMs tied to different software "A list of SBOMs tied to different software
or hardware versions."; or hardware versions.";
leaf version-info { leaf version-info {
type string; type string;
description description
"The version to which this SBOM refers."; "The version to which this SBOM refers.";
skipping to change at page 9, line 47 skipping to change at line 429
description description
"Which communication protocol to choose."; "Which communication protocol to choose.";
} }
} }
case sbom-contact-info { case sbom-contact-info {
leaf sbom-contact-uri { leaf sbom-contact-uri {
type inet:uri { type inet:uri {
pattern '((mailto)|(https?)|(tel)):.*'; pattern '((mailto)|(https?)|(tel)):.*';
} }
description description
"This MUST be either a tel, http, https, or "This MUST be a tel, an http, an https, or
mailto uri schema that customers can use to a mailto uri schema that customers can use to
contact someone for SBOM information."; contact someone for SBOM information.";
} }
} }
} }
leaf sbom-archive-list { leaf sbom-archive-list {
type inet:uri; type inet:uri;
description description
"This URI returns a JSON list of URLs that consist of "This URI returns a JSON list of URLs that consist of
SBOMs that were previously published for this SBOMs that were previously published for this
device. Publication dates can be found inside device. Publication dates can be found inside
the SBOMs."; the SBOMs.";
} }
choice vuln-retrieval-method { choice vuln-retrieval-method {
description description
"How to find vulnerability information"; "How to find vulnerability information.";
case cloud { case cloud {
leaf-list vuln-url { leaf-list vuln-url {
type inet:uri; type inet:uri;
description description
"List of statically located URLs that reference "List of statically located URLs that reference
vulnerability information"; vulnerability information.";
} }
} }
case vuln-contact-info { case vuln-contact-info {
leaf vuln-contact-uri { leaf vuln-contact-uri {
type inet:uri { type inet:uri {
pattern '((mailto)|(https?)|(tel)):.*'; pattern '((mailto)|(https?)|(tel)):.*';
} }
description description
"This MUST be either a tel, http, https, or "This MUST be a tel, an http, an https, or
mailto uri schema that customers can use to a mailto uri schema that customers can use to
contact someone for vulnerability information."; contact someone for vulnerability information.";
} }
} }
} }
} }
} }
augment "/mud:mud" { augment "/mud:mud" {
description description
"Add extension for software transparency."; "Add extension for software transparency.";
uses transparency-extension; uses transparency-extension;
} }
} }
<CODE ENDS> <CODE ENDS>
5. Examples 5. Examples
In this example MUD file that uses a cloud service, the modelX 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 presents a location of the SBOM in a URL. Note that the Access
file are NOT required, although they are a very good idea for IP- Control Lists (ACLs) in a MUD file are NOT required, although they
based devices. are a very good idea for IP-based devices.
5.1. Without ACLS 5.1. Without ACLS
This first MUD file demonstrates how to get SBOM and vulnerability This first MUD file demonstrates how to get SBOM and vulnerability
information without ACLs. information without ACLs.
{ {
"ietf-mud:mud": { "ietf-mud:mud": {
"mud-version": 1, "mud-version": 1,
"extensions": [ "extensions": [
"transparency" "transparency"
], ],
"mudtx:transparency": { "mudtx:transparency": {
"sbom-url": "https://iot.example.com/info/modelX/sbom.json", sboms: [ {
"version-info": "1.2",
"sbom-url": "https://iot.example.com/info/modelX/sbom.json"
} ],
"vuln-url" : [ "vuln-url" : [
"https://iotd.example.com/info/modelX/csaf.json" "https://iotd.example.com/info/modelX/csaf.json"
] ]
}, },
"mud-url": "https://iot.example.com/modelX.json", "mud-url": "https://iot.example.com/modelX.json",
"mud-signature": "https://iot.example.com/modelX.p7s", "mud-signature": "https://iot.example.com/modelX.p7s",
"last-update": "2022-01-05T13:29:12+00:00", "last-update": "2022-01-05T13:29:12+00:00",
"cache-validity": 48, "cache-validity": 48,
"is-supported": true, "is-supported": true,
"systeminfo": "retrieving vuln and SBOM info via a cloud service", "systeminfo": "retrieving vuln and SBOM info via a cloud service",
"mfg-name": "Example, Inc.", "mfg-name": "Example, Inc.",
"documentation": "https://iot.example.com/doc/modelX", "documentation": "https://iot.example.com/doc/modelX",
"model-name": "modelX" "model-name": "modelX"
} }
} }
The second example demonstrates that just SBOM information is The second example demonstrates that just SBOM information is
included from the cloud. included from the cloud.
{ {
"ietf-mud:mud": { "ietf-mud:mud": {
"mud-version": 1, "mud-version": 1,
"extensions": [ "extensions": [
"transparency" "transparency"
], ],
"mudtx:transparency": { "mudtx:transparency": {
"sbom-url": "https://iot.example.com/info/modelX/sbom.json" sboms: [ {
}, "version-info": "1.2",
"mud-url": "https://iot.example.com/modelX.json", "sbom-url": "https://iot.example.com/info/modelX/sbom.json"
"mud-signature": "https://iot.example.com/modelX.p7s", } ],
"last-update": "2022-01-05T13:29:12+00:00", },
"cache-validity": 48, "mud-url": "https://iot.example.com/modelX.json",
"is-supported": true, "mud-signature": "https://iot.example.com/modelX.p7s",
"systeminfo": "retrieving only SBOM info via a cloud service", "last-update": "2022-01-05T13:29:12+00:00",
"mfg-name": "Example, Inc.", "cache-validity": 48,
"documentation": "https://iot.example.com/doc/modelX", "is-supported": true,
"model-name": "modelX" "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 5.2. SBOM Located on the Device
In the next example, the SBOM is located on the device, and there is In the next example, the SBOM is located on the device, and there is
no vulnerability information provided. no vulnerability information provided.
{ {
"ietf-mud:mud": { "ietf-mud:mud": {
"mud-version": 1, "mud-version": 1,
skipping to change at page 13, line 4 skipping to change at line 568
"mud-signature": "https://iot.example.com/modelX.p7s", "mud-signature": "https://iot.example.com/modelX.p7s",
"last-update": "2022-01-05T13:29:47+00:00", "last-update": "2022-01-05T13:29:47+00:00",
"cache-validity": 48, "cache-validity": 48,
"is-supported": true, "is-supported": true,
"systeminfo": "retrieving SBOM info from a local source", "systeminfo": "retrieving SBOM info from a local source",
"mfg-name": "Example, Inc.", "mfg-name": "Example, Inc.",
"documentation": "https://iot.example.com/doc/modelX", "documentation": "https://iot.example.com/doc/modelX",
"model-name": "modelX" "model-name": "modelX"
} }
} }
In this example, the SBOM is retrieved from the device, while In this example, the SBOM is retrieved from the device, while
vulnerability information is available from the cloud. This is vulnerability information is available from the cloud. This is
likely a common case, because vendors may learn of vulnerability likely a common case because vendors may learn of vulnerability
information more frequently than they update software. information more frequently than they update software.
{ {
"ietf-mud:mud": { "ietf-mud:mud": {
"mud-version": 1, "mud-version": 1,
"extensions": [ "extensions": [
"transparency" "transparency"
], ],
"mudtx:transparency": { "mudtx:transparency": {
"sbom-local-well-known": "https", "sbom-local-well-known": "https",
"vuln-url" : [ "vuln-url" : [
"https://iotd.example.com/info/modelX/csaf.json" "https://iotd.example.com/info/modelX/csaf.json"
] ]
skipping to change at page 13, line 31 skipping to change at line 596
"mud-url": "https://iot-device.example.com/modelX.json", "mud-url": "https://iot-device.example.com/modelX.json",
"mud-signature": "https://iot-device.example.com/modelX.p7s", "mud-signature": "https://iot-device.example.com/modelX.p7s",
"last-update": "2022-01-05T13:25:14+00:00", "last-update": "2022-01-05T13:25:14+00:00",
"cache-validity": 48, "cache-validity": 48,
"is-supported": true, "is-supported": true,
"systeminfo": "mixed example: SBOM on device, vuln info in cloud", "systeminfo": "mixed example: SBOM on device, vuln info in cloud",
"mfg-name": "Example, Inc.", "mfg-name": "Example, Inc.",
"documentation": "https://iot-device.example.com/doc/modelX", "documentation": "https://iot-device.example.com/doc/modelX",
"model-name": "modelX" "model-name": "modelX"
} }
} }
5.3. Further contact required. 5.3. Further Contact Required
In this example, the network manager must take further steps to In this example, the network manager must take further steps to
retrieve SBOM information. Vulnerability information is still retrieve SBOM information. Vulnerability information is still
available. available.
{ {
"ietf-mud:mud": { "ietf-mud:mud": {
"mud-version": 1, "mud-version": 1,
"extensions": [ "extensions": [
"transparency" "transparency"
], ],
"ietf-mud-transparency:transparency": { "mudtx:transparency": {
"contact-info": "https://iot-device.example.com/contact-info.html", "contact-info": "https://iot-device.example.com/contact-info.html",
"vuln-url" : [ "vuln-url" : [
"https://iotd.example.com/info/modelX/csaf.json" "https://iotd.example.com/info/modelX/csaf.json"
] ]
}, },
"mud-url": "https://iot-device.example.com/modelX.json", "mud-url": "https://iot-device.example.com/modelX.json",
"mud-signature": "https://iot-device.example.com/modelX.p7s", "mud-signature": "https://iot-device.example.com/modelX.p7s",
"last-update": "2021-07-09T06:16:42+00:00", "last-update": "2021-07-09T06:16:42+00:00",
"cache-validity": 48, "cache-validity": 48,
"is-supported": true, "is-supported": true,
"systeminfo": "retrieving vuln and SBOM info via a cloud service", "systeminfo": "retrieving vuln and SBOM info via a cloud service",
"mfg-name": "Example, Inc.", "mfg-name": "Example, Inc.",
"documentation": "https://iot-device.example.com/doc/modelX", "documentation": "https://iot-device.example.com/doc/modelX",
"model-name": "modelX" "model-name": "modelX"
} }
} }
5.4. With ACLS 5.4. With ACLS
Finally, here is a complete example where the device provides SBOM Finally, here is a complete example where the device provides SBOM
and vulnerability information, as well as access-control information. and vulnerability information as well as access control information.
{ {
"ietf-mud:mud": { "ietf-mud:mud": {
"mud-version": 1, "mud-version": 1,
"extensions": [ "extensions": [
"transparency" "transparency"
], ],
"mudtx:transparency": { "mudtx:transparency": {
"sbom-local-well-known": "https", "sbom-local-well-known": "https",
"vuln-url" : [ "vuln-url" : [
"https://iotd.example.com/info/modelX/csaf.json" "https://iotd.example.com/info/modelX/csaf.json"
] ]
skipping to change at page 16, line 19 skipping to change at line 715
}, },
"actions": { "actions": {
"forwarding": "accept" "forwarding": "accept"
} }
} }
] ]
} }
} }
] ]
} }
} }
At this point, the management system can attempt to retrieve the At this point, the management system can attempt to retrieve the
SBOM, and determine which format is in use through the content-type SBOM, determine which format is in use through the Content-Type
header on the response to a GET request, independently repeat the header on the response to a GET request, independently repeat the
process for vulnerability information, and apply ACLs, as process for vulnerability information, and apply ACLs as appropriate.
appropriate.
6. Security Considerations 6. Security Considerations
This document describes a schema for discovering the location of This document describes a schema for discovering the location of
information relating to software transparency, and does not specify information relating to software transparency and does not specify
the access model for the information itself. In particular, the YANG the access model for the information itself. In particular, the YANG
module specified in this document is not necessarily intended to be module specified in this document is not necessarily intended to be
accessed via regular network management protocols, such as the accessed via regular network management protocols, such as NETCONF
NETCONF [RFC6241] or RESTCONF [RFC8040], and hence the regular [RFC6241] or RESTCONF [RFC8040], and hence the regular security
security considerations for such usage are not considered here. considerations for such usage are not considered here.
We describe below protections relating to both discovery and some Below, we describe protections relating to both discovery and some
advice on protecting the underlying SBOM/vulnerability information. advice on protecting the underlying SBOM and vulnerability
information.
The model specifies both encrypted and unencrypted means to retrieve The model specifies both encrypted and unencrypted means to retrieve
information. This is a matter of pragmatism. Unencrypted information. This is a matter of pragmatism. Unencrypted
communications allow for manipulation of information being retrieved. communications allow for manipulation of information being retrieved.
Therefore, it is RECOMMENDED that implementations offer a means to Therefore, it is RECOMMENDED that implementations offer a means to
configure endpoints so that they may make use of TLS or DTLS. configure endpoints so that they may make use of TLS or DTLS.
The ietf-mud-transparency module has no operational impact on the The ietf-mud-transparency module has no operational impact on the
element itself, and is used to discover state information that may be 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 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 read- made writeable, this only indicates a change in how to retrieve read-
only elements. There is no means, for instance, to upload an SBOM. only elements. There are no means, for instance, to upload an SBOM.
Additional risks are discussed below, and are applicable to all nodes Additional risks are discussed below and are applicable to all nodes
within the transparency container. within the transparency container.
If an attacker modifies the elements, they may misdirect automation If an attacker modifies the elements, they may misdirect automation
to retrieve a different set of URLs than was intended by the to retrieve a different set of URLs than was intended by the
designer. This in turn leads to two specific sets of risks: designer. This in turn leads to two specific sets of risks:
* the information retrieved would be false. * the information retrieved would be false
* the URLs themselves point to malware. * the URLs themselves point to malware
To address either risk, any change in a URL, and in particular to the To address either of these risks or any tampering of a URL:
authority section, two approaches may be used:
* test any cloud-based URL against a reputation service. * test any cloud-based URL against a reputation service
* provide the administrator an opportunity to approve further * provide the administrator an opportunity to approve further
procesisng when the authority changes to one not known to be processing when the authority changes to one not known to be
reputable. reputable
SBOMs provide an inventory of software. Knowledge of which specific SBOMs provide an inventory of software. Knowledge of which specific
software is loaded on a system can aid an attacker in identifying an software is loaded on a system can aid an attacker in identifying an
appropriate exploit for a known vulnerability or guide the appropriate exploit for a known vulnerability or guide the
development of novel exploit against this system. However, if development of novel exploit against this system. However, if
software is available to an attacker, the attacker may well already software is available to an attacker, the attacker may already be
be able to derive this very same software inventory. When this able to derive this very same software inventory. When this
information resides on the endpoint itself, the endpoint SHOULD NOT information resides on the endpoint itself, the endpoint SHOULD NOT
provide unrestricted access to the well-known URL by default. provide unrestricted access to the well-known URL by default.
Other servers that offer the data MAY restrict access to SBOM Other servers that offer the data MAY restrict access to SBOM
information using appropriate authorization semantics within HTTP. information using appropriate authorization semantics within HTTP.
One way to do this would be to issue a certificate to the client for One way to do this would be to issue a certificate to the client for
this purpose after a registration process has taken place. Another this purpose after a registration process has taken place. Another
approach would involve the use of OAUTH in combination. In approach would involve the use of OAuth in combination. In
particular, if a system attempts to retrieve an SBOM via HTTP or COAP particular, if a system attempts to retrieve an SBOM via HTTP or CoAP
and the client is not authorized, the server MUST produce an and the client is not authorized, the server MUST produce an
appropriate error, with instructions on how to register a particular appropriate error with instructions on how to register a particular
client. client.
Another risk is a skew in the SBOM listing and the actual software Another risk is a skew in the SBOM listing and the actual software
inventory of a device/container. For example, a manufacturer may inventory of a device/container. For example, a manufacturer may
update the SBOM on its server, but an individual device has not been update the SBOM on its server, but an individual device has not been
upgraded yet. This may result in an incorrect policy being applied 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 to a device. A unique mapping of a device's software version and its
SBOM can minimize this risk. SBOM can minimize this risk.
To further mitigate attacks against a device, manufacturers SHOULD To further mitigate attacks against a device, manufacturers SHOULD
skipping to change at page 18, line 26 skipping to change at line 806
databases as NIST's National Vulnerability Database [NISTNVD]. It is databases as NIST's National Vulnerability Database [NISTNVD]. It is
possible that vendors may wish to release information early to some possible that vendors may wish to release information early to some
customers. We do not discuss here whether that is a good idea, but customers. We do not discuss here whether that is a good idea, but
if it is employed, then appropriate access controls and authorization if it is employed, then appropriate access controls and authorization
SHOULD be applied to that information. SHOULD be applied to that information.
7. IANA Considerations 7. IANA Considerations
7.1. MUD Extension 7.1. MUD Extension
The IANA is requested to add "transparency" to the MUD extensions IANA has added "transparency" to the "MUD Extensions" registry
registry as follows: [RFC8520] as follows:
Extension Name: transparency Value: transparency
Standard reference: This document Reference: RFC 9472
7.2. YANG Registration 7.2. YANG Registration
The following YANG module should be registered in the "YANG Module IANA has registered the following YANG module in the "YANG Module
Names" registry: Names" registry [RFC6020]:
Name: ietf-mud Name: ietf-mud-transparency
URN: urn:ietf:params:xml:ns:yang:ietf-mud-transparency Namespace: urn:ietf:params:xml:ns:yang:ietf-mud-transparency
Prefix: mudtx Maintained by IANA: N
Registrant contact: The IESG Prefix: mudtx
Reference: This memo Reference: RFC 9472
The following XML registration is requested: The following URI has been registered in the "IETF XML Registry"
[RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-mud-transparency URI: urn:ietf:params:xml:ns:yang:ietf-mud-transparency
Registrant Contact: IESG Registrant Contact: IESG
XML: None. Namespace URIs do not represent an XML specification. XML: None. Namespace URIs do not represent an XML specification.
7.3. Well-Known Prefix 7.3. Well-Known Prefix
The following well known URI is requested in accordance with IANA has added the following URI suffix to the "Well-Known URIs"
[RFC8615]: registry in accordance with [RFC8615]:
URI suffix: "sbom"
Change controller: "IETF"
Specification document: This memo
Related information: See ISO/IEC 5962:2021 and SPDX.org
8. Acknowledgments
Thanks to Russ Housley, Dick Brooks, Tom Petch, Nicolas Comstedt, who URI Suffix: sbom
provided review comments. Change Controller: IETF
Reference: RFC 9472
Status: permanent
Related Information: See ISO/IEC 5962:2021 and SPDX.org
9. References 8. References
9.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>. <https://www.rfc-editor.org/info/rfc6241>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013, RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>. <https://www.rfc-editor.org/info/rfc6991>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252, Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014, DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/info/rfc7252>. <https://www.rfc-editor.org/info/rfc7252>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>. <https://www.rfc-editor.org/info/rfc8040>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
skipping to change at page 20, line 14 skipping to change at line 900
[RFC8615] Nottingham, M., "Well-Known Uniform Resource Identifiers [RFC8615] Nottingham, M., "Well-Known Uniform Resource Identifiers
(URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019, (URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019,
<https://www.rfc-editor.org/info/rfc8615>. <https://www.rfc-editor.org/info/rfc8615>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, [RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110, Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022, DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/info/rfc9110>. <https://www.rfc-editor.org/info/rfc9110>.
9.2. Informative References 8.2. Informative References
[CSAF] Rock, L., Ed., Hagen, S., Ed., and T. Schmidt, Ed., [CSAF] Rock, L., Ed., Hagen, S., Ed., and T. Schmidt, Ed.,
"Common Security Advisory Framework Version 2.0", November "Common Security Advisory Framework Version 2.0", OASIS
2022, <https://docs.oasis-open.org/csaf/csaf/v2.0/csaf- Standard, November 2022, <https://docs.oasis-
v2.0.html>. open.org/csaf/csaf/v2.0/csaf-v2.0.html>.
[CVRF] Hagen, S., Ed., "Common Vulnerability Reporting Framework [CVRF] Hagen, S., Ed., "CSAF Common Vulnerability Reporting
(CVRF) Version 1.2", September 2017, <https://docs.oasis- Framework (CVRF) Version 1.2", Committee Specification 01,
open.org/csaf/csaf-cvrf/v1.2/csaf-cvrf-v1.2.pdf>. September 2017, <https://docs.oasis-open.org/csaf/csaf-
cvrf/v1.2/csaf-cvrf-v1.2.pdf>.
[CycloneDX12] [CycloneDX15]
cyclonedx.org, "CycloneDX XML Reference v1.2", May 2020. CycloneDX, "CycloneDX v1.5 JSON Reference", Version 1.5.0,
<https://cyclonedx.org/docs/1.5/json>.
[EO2021] Biden, J., "Executive Order 14028, Improving the Nations [EO2021] Biden, J., "Executive Order on Improving the Nation's
Cybersecurity", May 2021. Cybersecurity", EO 14028, May 2021.
[NISTNVD] NIST, "National Vulnerability Database", n.d., [NISTNVD] NIST, "National Vulnerability Database",
<https://nvd.nist.gov>. <https://nvd.nist.gov>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>. <https://www.rfc-editor.org/info/rfc8340>.
[SPDX] The Linux Foundation, "SPDX Specification V2.3", 2022, [SPDX] The Linux Foundation, "The Software Package Data Exchange
(SPDX) Specification", Version 2.3, 2022,
<https://spdx.github.io/spdx-spec/v2.3/>. <https://spdx.github.io/spdx-spec/v2.3/>.
Appendix A. Changes from Earlier Versions Acknowledgments
[[This section to be removed by RFC Editor]]
Please see https://github.com/elear/mud-sbom for changes. Thanks to Russ Housley, Dick Brooks, Tom Petch, and Nicolas Comstedt,
who provided review comments.
Authors' Addresses Authors' Addresses
Eliot Lear Eliot Lear
Cisco Systems Cisco Systems
Richtistrasse 7 Richtistrasse 7
CH-8304 Wallisellen CH-8304 Wallisellen
Switzerland Switzerland
Phone: +41 44 878 9200 Phone: +41 44 878 9200
Email: lear@cisco.com Email: lear@cisco.com
Scott Rose Scott Rose
NIST NIST
100 Bureau Dr 100 Bureau Dr.
Gaithersburg MD, 20899 Gaithersburg, MD 20899
United States of America United States of America
Phone: +1 301-975-8439 Phone: +1 301-975-8439
Email: scott.rose@nist.gov Email: scott.rose@nist.gov
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