Internet DRAFT - draft-ietf-opsawg-sbom-access
draft-ietf-opsawg-sbom-access
Network Working Group E. Lear
Internet-Draft Cisco Systems
Intended status: Standards Track S. Rose
Expires: 30 October 2023 NIST
28 April 2023
Discovering and Retrieving Software Transparency and Vulnerability
Information
draft-ietf-opsawg-sbom-access-18
Abstract
To improve cybersecurity posture, automation is necessary to locate
the software a device is using, and whether that software has known
vulnerabilities, and what, if any recommendations suppliers may have.
This memo extends the MUD YANG schema to provide the locations of
software bills of materials (SBOMS) and to vulnerability information
by introducing a transparency schema.
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 30 October 2023.
Copyright Notice
Copyright (c) 2023 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
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 . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.1. Without ACLS . . . . . . . . . . . . . . . . . . . . . . 11
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 . . . . . . . . . . . . . . . . . . . . . . . 20
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, this memo seeks to answer two classes of questions to the
scale of tens of thousands of devices and a large variety of types of
devices. Those questions are as the following:
* 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. That is, the model is
intended to facilitate discovery, and on its own provides no access
to the underlying data.
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
administrators the state of any known vulnerabilities on a system.
SBOM and vulnerability information can be used in concert with other
sources of vulnerability information. For a network management tool
could discover that a system makes use of a particular set of
software components, searches a national vulnerability database to
determine known vulnerabilities, and then applies information
provided the manufacturer through this mechanism to produce a
vulnerability report. That 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.
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The mechanisms specified in this document are meant to address two
use cases:
* 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 methods:
* on devices themselves
* on a website (e.g., via URI)
* through some form of out-of-band contact with the supplier.
Using the first method, devices will have interfaces that permit
direct retrieval. Examples of these interfaces might be an HTTP
[RFC9110], or COAP [RFC7252] endpoint for retrieval. There may also
be private interfaces as well.
Using the second method, when a device does not have an appropriate
retrieval interface, but one is directly available from the
manufacturer, a URI to that information is discovered through
interfaces such as MUD via DHCP or bootstrapping and ownership
transfer mechanisms.
Using the third method, 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 information. Further
queries may be necessary based on the content and structure of the
response.
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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.
1.1. How This Information Is Retrieved
Section 4 describes a data model to extend the MUD file format to
carry SBOM and vulnerability information. Section 1.5 of RFC8520
describes mechanisms by which devices can emit a URL to point to this
file. Additionally, devices can share this URL either through
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
device.
Note that vulnerability and SBOM information are likely to change at
different rates. MUD's cache-validity node provides 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 from the device or from
a remote 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.
If multiple SBOMs are intended to be supported in the same file, the
media type should properly reflect that. For example, one might make
use of application/{someformat}+json-seq. It is left to those
supporting those formats to make the appropriate registrations in
this case.
Some formats may support both vulnerability and software inventory
information. When both vulnerability and software inventory
information is available from the same URL, both sbom-url and members
of the vuln-url list MUST indicate that. Network management systems
retrieving this information MUST take note that the identical
resource is being retrieved rather than retrieving it twice.
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2. The well-known transparency endpoint set
A well-known endpoint is defined:
* "/.well-known/sbom" retrieves an SBOM.
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? identityref
| +--:(sbom-contact-info)
| +--rw sbom-contact-uri? inet:uri
+--rw sbom-archive-list? inet:uri
+--rw (vuln-retrieval-method)?
+--:(cloud)
| +--rw vuln-url* inet:uri
+--:(vuln-contact-info)
+--rw vuln-contact-uri? inet:uri
See [RFC8340] for a description of YANG trees.
4. The mud-sbom augmentation to the MUD YANG model
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<CODE BEGINS>
file "ietf-mud-transparency@2023-01-12.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: https://datatracker.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) 2023 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 Revised 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,
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they appear in all capitals, as shown here. ";
revision 2023-01-12 {
description
"Initial proposed standard.";
reference
"RFC XXXX: Discovering and Retrieving Software Transparency
and Vulnerability Information";
}
identity local-type {
description
"Base identity for local-well-known choices";
}
identity http {
base mudtx:local-type;
description
"Use http[RFC7231] (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";
}
identity https {
base mudtx:local-type;
description
"Use https (secure) to retrieve SBOM information. See
RFC 9110.";
}
identity coap {
base mudtx:local-type;
description
"Use COAP [RFC7252] (insecure) to retrieve SBOM. This method
is NOT RECOMMENDED, although it may be unavoidable
for certain classes of implementations/deployments.";
}
identity coaps {
base mudtx:local-type;
description
"Use COAPS (secure) to retrieve SBOM [RFC7252]";
}
grouping transparency-extension {
description
"This grouping provides a means to describe the location of
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software bills of material and vulnerability descriptions.";
container transparency {
description
"Container of methods to get SBOMs and vulnerability
information.";
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 software
or hardware versions.";
leaf version-info {
type string;
description
"The version to which this SBOM refers.";
}
leaf sbom-url {
type inet:uri {
pattern '((coaps?)|(https?)):.*';
}
description
"A statically located URL.";
}
}
}
case local-well-known {
leaf sbom-local-well-known {
type identityref {
base mudtx:local-type;
}
description
"Which communication protocol to choose.";
}
}
case sbom-contact-info {
leaf sbom-contact-uri {
type inet:uri {
pattern '((mailto)|(https?)|(tel)):.*';
}
description
"This MUST be either a tel, http, https, or
mailto uri schema that customers can use to
contact someone for SBOM information.";
}
}
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}
leaf sbom-archive-list {
type inet:uri;
description
"This URI returns a JSON list of URLs that consist of
SBOMs that were previously published for this
device. Publication dates can be found inside
the SBOMs.";
}
choice vuln-retrieval-method {
description
"How to find vulnerability information";
case cloud {
leaf-list vuln-url {
type inet:uri;
description
"List of statically located URLs that reference
vulnerability information";
}
}
case vuln-contact-info {
leaf vuln-contact-uri {
type inet:uri {
pattern '((mailto)|(https?)|(tel)):.*';
}
description
"This MUST be either a tel, http, https, or
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>
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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.
{
"ietf-mud:mud": {
"mud-version": 1,
"extensions": [
"transparency"
],
"mudtx:transparency": {
"sbom-url": "https://iot.example.com/info/modelX/sbom.json",
"vuln-url" : [
"https://iotd.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 from the cloud.
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{
"ietf-mud:mud": {
"mud-version": 1,
"extensions": [
"transparency"
],
"mudtx:transparency": {
"sbom-url": "https://iot.example.com/info/modelX/sbom.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 only 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 the next example, the SBOM is located on the device, and there is
no vulnerability information provided.
{
"ietf-mud:mud": {
"mud-version": 1,
"extensions": [
"transparency"
],
"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 SBOM info from a local source",
"mfg-name": "Example, Inc.",
"documentation": "https://iot.example.com/doc/modelX",
"model-name": "modelX"
}
}
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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.
{
"ietf-mud:mud": {
"mud-version": 1,
"extensions": [
"transparency"
],
"mudtx:transparency": {
"sbom-local-well-known": "https",
"vuln-url" : [
"https://iotd.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": "mixed example: SBOM on device, vuln info in cloud",
"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://iotd.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": [
"transparency"
],
"mudtx:transparency": {
"sbom-local-well-known": "https",
"vuln-url" : [
"https://iotd.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,
"is-supported": true,
"systeminfo": "retrieving vuln and SBOM info via a cloud service",
"mfg-name": "Example, Inc.",
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"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",
"aces": {
"ace": [
{
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"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
This document describes a schema for discovering the location of
information relating to software transparency, and does not specify
the access model for the information itself. In particular, the YANG
module specified in this document is not necessarily intended to be
accessed via regular network management protocols, such as the
NETCONF [RFC6241] or RESTCONF [RFC8040], and hence the regular
security considerations for such usage are not considered here.
We describe below protections relating to both discovery and some
advice on protecting the underlying SBOM/vulnerability information.
The model specifies both encrypted and unencrypted means to retrieve
information. This is a matter of pragmatism. Unencrypted
communications allow for manipulation of information being retrieved.
Therefore, it is RECOMMENDED that implementations offer a means to
configure endpoints so that they may make use of TLS or DTLS.
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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 read-
only elements. There is no means, for instance, to upload an SBOM.
Additional risks 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, two approaches may be used:
* test any cloud-based URL against a reputation service.
* provide the administrator an opportunity to approve further
procesisng when the authority changes to one not known to be
reputable.
SBOMs provide an inventory of software. Knowledge of which specific
software is loaded on a system can aid an attacker in identifying an
appropriate exploit for a known vulnerability or guide the
development of novel exploit against this system. However, if
software is available to an attacker, the attacker may well already
be able to derive this very same software inventory. When this
information resides on the endpoint itself, the endpoint SHOULD NOT
provide unrestricted access to the well-known URL by default.
Other servers that offer the data MAY restrict access to SBOM
information using appropriate authorization semantics within HTTP.
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
approach would involve the use of OAUTH in combination. In
particular, if a system attempts to retrieve an SBOM via HTTP or COAP
and the client is not authorized, the server MUST produce an
appropriate error, with instructions on how to register a particular
client.
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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 network access controls.
Vulnerability information is generally made available to such
databases as NIST's National Vulnerability Database [NISTNVD]. It is
possible that vendors 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 that information.
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
The following XML registration is requested:
URI: urn:ietf:params:xml:ns:yang:ietf-mud-transparency
Registrant Contact: IESG
XML: None. Namespace URIs do not represent an XML specification.
7.3. Well-Known Prefix
The following well known URI is requested in accordance with
[RFC8615]:
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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
provided review 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>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/info/rfc7252>.
[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>.
[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>.
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[RFC8615] Nottingham, M., "Well-Known Uniform Resource Identifiers
(URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019,
<https://www.rfc-editor.org/info/rfc8615>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/info/rfc9110>.
9.2. Informative References
[CSAF] Rock, L., Ed., Hagen, S., Ed., and T. Schmidt, Ed.,
"Common Security Advisory Framework Version 2.0", November
2022, <https://docs.oasis-open.org/csaf/csaf/v2.0/csaf-
v2.0.html>.
[CVRF] Hagen, S., 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]
cyclonedx.org, "CycloneDX XML Reference v1.2", May 2020.
[EO2021] Biden, J., "Executive Order 14028, Improving the Nations
Cybersecurity", May 2021.
[NISTNVD] NIST, "National Vulnerability Database", n.d.,
<https://nvd.nist.gov>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[SPDX] The Linux Foundation, "SPDX Specification V2.3", 2022,
<https://spdx.github.io/spdx-spec/v2.3/>.
Appendix A. Changes from Earlier Versions
[[This section to be removed by RFC Editor]]
Please see https://github.com/elear/mud-sbom for changes.
Authors' Addresses
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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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