draft-ietf-opsawg-sbom-access-04.txt   draft-ietf-opsawg-sbom-access-05.txt 
Network Working Group E. Lear Network Working Group E. Lear
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Intended status: Standards Track S. Rose Intended status: Standards Track S. Rose
Expires: 9 July 2022 NIST Expires: 7 September 2022 NIST
5 January 2022 6 March 2022
Discovering and Retrieving Software Transparency and Vulnerability Discovering and Retrieving Software Transparency and Vulnerability
Information Information
draft-ietf-opsawg-sbom-access-04 draft-ietf-opsawg-sbom-access-05
Abstract Abstract
To improve cybersecurity posture, automation is necessary to locate To improve cybersecurity posture, automation is necessary to locate
what software is running on a device, whether that software has known what software is running on a device, whether that software has known
vulnerabilities, and what, if any recommendations suppliers may have. vulnerabilities, and what, if any recommendations suppliers may have.
This memo specifies a model to provide access to this information. This memo specifies a model to provide access to this information.
It may optionally be discovered through manufacturer usage It may optionally be discovered through manufacturer usage
descriptions. descriptions.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on 9 July 2022. This Internet-Draft will expire on 7 September 2022.
Copyright Notice Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the Copyright (c) 2022 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 (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License. provided without warranty as described in the Revised BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Cases Not Addressed . . . . . . . . . . . . . . . . . . . 5 1.1. How This Information Is Retrieved . . . . . . . . . . . . 5
1.2. How This Information Is Retrieved . . . . . . . . . . . . 5 1.2. Formats . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Formats . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3. Discussion points . . . . . . . . . . . . . . . . . . . . 5
1.4. Discussion points . . . . . . . . . . . . . . . . . . . . 6
2. The well-known transparency endpoint set . . . . . . . . . . 6 2. The well-known transparency endpoint set . . . . . . . . . . 6
3. The mud-transparency extension model extension . . . . . . . 6 3. The mud-transparency extension model extension . . . . . . . 6
4. The mud-sbom augmentation to the MUD YANG model . . . . . . . 7 4. The mud-sbom augmentation to the MUD YANG model . . . . . . . 6
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. Without ACLS . . . . . . . . . . . . . . . . . . . . . . 10 5.1. Without ACLS . . . . . . . . . . . . . . . . . . . . . . 10
5.2. SBOM Located on the Device . . . . . . . . . . . . . . . 12 5.2. SBOM Located on the Device . . . . . . . . . . . . . . . 12
5.3. Further contact required. . . . . . . . . . . . . . . . . 13 5.3. Further contact required. . . . . . . . . . . . . . . . . 13
5.4. With ACLS . . . . . . . . . . . . . . . . . . . . . . . . 14 5.4. With ACLS . . . . . . . . . . . . . . . . . . . . . . . . 14
6. Security Considerations . . . . . . . . . . . . . . . . . . . 16 6. Security Considerations . . . . . . . . . . . . . . . . . . . 16
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
7.1. MUD Extension . . . . . . . . . . . . . . . . . . . . . . 17 7.1. MUD Extension . . . . . . . . . . . . . . . . . . . . . . 18
7.2. YANG Registration . . . . . . . . . . . . . . . . . . . . 17 7.2. YANG Registration . . . . . . . . . . . . . . . . . . . . 18
7.3. Well-Known Prefix . . . . . . . . . . . . . . . . . . . . 17 7.3. Well-Known Prefix . . . . . . . . . . . . . . . . . . . . 18
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1. Normative References . . . . . . . . . . . . . . . . . . 18 9.1. Normative References . . . . . . . . . . . . . . . . . . 19
9.2. Informative References . . . . . . . . . . . . . . . . . 18 9.2. Informative References . . . . . . . . . . . . . . . . . 20
Appendix A. Changes from Earlier Versions . . . . . . . . . . . 19 Appendix A. Changes from Earlier Versions . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction 1. Introduction
A number of activities have been working to improve visibility to A number of activities have been working to improve visibility to
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, we seek to answer two classes of questions *at scale*: Put simply, we seek to answer two classes of questions *at scale*:
* Is this system vulnerable to a particular vulnerability? * Is this system vulnerable to a particular vulnerability?
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well-known URI to retrieve a system's SBOM or vulnerability well-known URI to retrieve a system's SBOM or vulnerability
information. Further queries may be necessary based on the content information. Further queries may be necessary based on the content
and structure of the response. and structure of the response.
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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
1.1. Cases Not Addressed 1.1. How This Information Is Retrieved
[ This section to be removed prior to publication ]
A separate use case may be addressed in future versions of this
document:
* Related to the application layer, software as a service may
involve multiple backend systems, depending on many factors. One
example might be a large cloud-based service that offers
spreadsheets, email, and document authoring and management.
Depending on what service is being used, a different set of back
end services may in turn be invoking different software that
should be listed.
The reason why this use case isn't addressed here is that it may be
better addressed inline within HTML. Further discussion is required.
1.2. How This Information Is Retrieved
For devices that can emit a URL or can establish a well-known URI, 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 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 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 mechanism is semi-automated (someone has to scan the QR code or enter
the URL). the URL).
Note that vulnerability and SBOM information is likely to change at Note that vulnerability and SBOM information is likely to change at
different rates. The MUD semantics provide a way for manufacturers different rates. The MUD semantics provide a way for manufacturers
to control how often tooling should check for those changes through to control how often tooling should check for those changes through
the cache-validity node. the cache-validity node.
1.3. Formats 1.2. 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 directly from the information. When these are retrieved either directly from the
device or directly from a web server, tools will need to observe the device or directly from a web server, tools will need to observe the
content-type header to determine precisely which format is being content-type header to determine precisely which format is being
transmitted. Because IoT devices in particular have limited transmitted. Because IoT devices in particular have limited
capabilities, use of a specific Accept: header in HTTP or the Accept capabilities, use of a specific Accept: header in HTTP or the Accept
Option in CoAP is NOT RECOMMENDED. Instead, backend tooling is Option in CoAP is NOT RECOMMENDED. Instead, backend tooling is
encouraged to support all known formats, and SHOULD silently discard encouraged to support all known formats, and SHOULD silently discard
SBOM information sent with a media type that is not understood. SBOM information sent with a media type that is not understood.
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 location, both sbom and vuln information is available from the same location, both sbom and vuln
nodes MUST indicate that. Network management systems retrieving this nodes MUST indicate that. Network management systems retrieving this
information MUST take note that the identical resource is being information MUST take note that the identical resource is being
retrieved rather than retrieving it twice. retrieved rather than retrieving it twice.
1.4. Discussion points 1.3. Discussion points
The following is discussion to be removed at time of RFC publication. The following is discussion to be removed at time of RFC publication.
* Is the model structured correctly? * Is the model structured correctly?
* Are there other retrieval mechanisms that need to be specified? * Are there other retrieval mechanisms that need to be specified?
* Do we need to be more specific in how to authenticate and retrieve * Do we need to be more specific in how to authenticate and retrieve
SBOMs? SBOMs?
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"A statically located URI."; "A statically located URI.";
} }
} }
} }
case local-well-known { case local-well-known {
leaf sbom-local-well-known { leaf sbom-local-well-known {
type enumeration { type enumeration {
enum http { enum http {
description description
"Use http (insecure) to retrieve "Use http (insecure) to retrieve
SBOM information."; 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 { enum https {
description description
"Use https (secure) to retrieve SBOM information."; "Use https (secure) to retrieve SBOM information.";
} }
enum coap { enum coap {
description description
"Use COAP (insecure) to retrieve SBOM"; "Use COAP (insecure) to retrieve SBOM. This method
is NOT RECOMMENDED, although it may be unavoidable
for certain classes of implementations/deployments.";
} }
enum coaps { enum coaps {
description description
"Use COAPS (secure) to retrieve SBOM"; "Use COAPS (secure) to retrieve SBOM";
} }
enum openc2 { enum openc2 {
description description
"Use OpenC2 endpoint. "Use OpenC2 endpoint.
This is https://{host}/.well-known/openc2"; This is https://{host}/.well-known/openc2";
} }
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} }
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, and 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
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.
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 SBOMs provide an inventory of software. If software is available to
an attacker, the attacker may well already be able to derive this an attacker, the attacker may well already be able to derive this
very same software inventory. Manufacturers MAY restrict access to very same software inventory. Manufacturers MAY restrict access to
SBOM information using appropriate authorization semantics within SBOM information using appropriate authorization semantics within
HTTP. In particular, if a system attempts to retrieve an SBOM via HTTP. In particular, if a system attempts to retrieve an SBOM via
HTTP and the client is not authorized, the server MUST produce an HTTP 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. One example may be to issue a certificate to the client for client. One example may 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
example would involve the use of OAUTH in combination with a example would involve the use of OAUTH in combination with a
federations of SBOM servers. federations of SBOM servers.
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
recommend access controls through the normal MUD mechanism. recommend access controls.
Vulnerability information is generally made available to such Vulnerability information is generally made available to such
databases as NIST's National Vulnerability Database. It is possible databases as NIST's National Vulnerability Database. It is possible
that vendor may wish to release information early to some customers. 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 We do not discuss here whether that is a good idea, but if it is
employed, then appropriate access controls and authorization would be employed, then appropriate access controls and authorization SHOULD
applied to the vulnerability resource. be applied to the vulnerability resource.
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 The IANA is requested to add "transparency" to the MUD extensions
registry as follows: registry as follows:
Extension Name: transparency Extension Name: transparency
Standard reference: This document Standard reference: This document
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9. References 9. References
9.1. Normative References 9.1. 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>.
[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", [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>.
[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 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[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 [RFC8520] Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage
Description Specification", RFC 8520, Description Specification", RFC 8520,
DOI 10.17487/RFC8520, March 2019, DOI 10.17487/RFC8520, March 2019,
<https://www.rfc-editor.org/info/rfc8520>. <https://www.rfc-editor.org/info/rfc8520>.
[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>.
9.2. Informative References 9.2. Informative References
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