--- 1/draft-ietf-opsawg-sbom-access-04.txt 2022-03-06 02:13:09.593132765 -0800 +++ 2/draft-ietf-opsawg-sbom-access-05.txt 2022-03-06 02:13:09.633133761 -0800 @@ -1,20 +1,20 @@ Network Working Group E. Lear Internet-Draft Cisco Systems Intended status: Standards Track S. Rose -Expires: 9 July 2022 NIST - 5 January 2022 +Expires: 7 September 2022 NIST + 6 March 2022 Discovering and Retrieving Software Transparency and Vulnerability Information - draft-ietf-opsawg-sbom-access-04 + draft-ietf-opsawg-sbom-access-05 Abstract To improve cybersecurity posture, automation is necessary to locate what software is running on a device, whether that software has known vulnerabilities, and what, if any recommendations suppliers may have. This memo specifies a model to provide access to this information. It may optionally be discovered through manufacturer usage descriptions. @@ -26,62 +26,61 @@ 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 9 July 2022. + This Internet-Draft will expire on 7 September 2022. Copyright Notice Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved. 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. Cases Not Addressed . . . . . . . . . . . . . . . . . . . 5 - 1.2. How This Information Is Retrieved . . . . . . . . . . . . 5 - 1.3. Formats . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 1.4. Discussion points . . . . . . . . . . . . . . . . . . . . 6 + 1.1. How This Information Is Retrieved . . . . . . . . . . . . 5 + 1.2. Formats . . . . . . . . . . . . . . . . . . . . . . . . . 5 + 1.3. Discussion points . . . . . . . . . . . . . . . . . . . . 5 2. The well-known transparency endpoint set . . . . . . . . . . 6 3. The mud-transparency extension model extension . . . . . . . 6 - 4. The mud-sbom augmentation to the MUD YANG model . . . . . . . 7 + 4. The mud-sbom augmentation to the MUD YANG model . . . . . . . 6 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.1. Without ACLS . . . . . . . . . . . . . . . . . . . . . . 10 5.2. SBOM Located on the Device . . . . . . . . . . . . . . . 12 5.3. Further contact required. . . . . . . . . . . . . . . . . 13 5.4. With ACLS . . . . . . . . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 16 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 - 7.1. MUD Extension . . . . . . . . . . . . . . . . . . . . . . 17 - 7.2. YANG Registration . . . . . . . . . . . . . . . . . . . . 17 - 7.3. Well-Known Prefix . . . . . . . . . . . . . . . . . . . . 17 - 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 - 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 - 9.1. Normative References . . . . . . . . . . . . . . . . . . 18 - 9.2. Informative References . . . . . . . . . . . . . . . . . 18 - Appendix A. Changes from Earlier Versions . . . . . . . . . . . 19 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 + 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 + 7.1. MUD Extension . . . . . . . . . . . . . . . . . . . . . . 18 + 7.2. YANG Registration . . . . . . . . . . . . . . . . . . . . 18 + 7.3. Well-Known Prefix . . . . . . . . . . . . . . . . . . . . 18 + 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19 + 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 + 9.1. Normative References . . . . . . . . . . . . . . . . . . 19 + 9.2. Informative References . . . . . . . . . . . . . . . . . 20 + Appendix A. Changes from Earlier Versions . . . . . . . . . . . 20 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 1. Introduction A number of activities have been working to improve visibility to what software is running on a system, and what vulnerabilities that software may have[EO2021]. Put simply, we seek to answer two classes of questions *at scale*: * Is this system vulnerable to a particular vulnerability? @@ -175,71 +174,53 @@ well-known URI to retrieve a system's SBOM or vulnerability information. Further queries may be necessary based on the content and structure of the response. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. -1.1. Cases Not Addressed - - [ 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 +1.1. How This Information Is Retrieved For devices that can emit a URL or can establish a well-known URI, the mechanism may be highly automated. For devices that have a URL in either their documentation or within a QR code on a box, the mechanism is semi-automated (someone has to scan the QR code or enter the URL). Note that vulnerability and SBOM information is likely to change at different rates. The MUD semantics provide a way for manufacturers to control how often tooling should check for those changes through the cache-validity node. -1.3. Formats +1.2. Formats There are multiple ways to express both SBOMs and vulnerability information. When these are retrieved either directly from the device or directly from a web server, tools will need to observe the content-type header to determine precisely which format is being transmitted. Because IoT devices in particular have limited capabilities, use of a specific Accept: header in HTTP or the Accept Option in CoAP is NOT RECOMMENDED. Instead, backend tooling is encouraged to support all known formats, and SHOULD silently discard SBOM information sent with a media type that is not understood. Some formats may support both vulnerability and software inventory information. When both vulnerability and software inventory information is available from the same location, both sbom and vuln nodes MUST indicate that. Network management systems retrieving this information MUST take note that the identical resource is being retrieved rather than retrieving it twice. -1.4. Discussion points +1.3. Discussion points The following is discussion to be removed at time of RFC publication. * Is the model structured correctly? * Are there other retrieval mechanisms that need to be specified? * Do we need to be more specific in how to authenticate and retrieve SBOMs? @@ -372,29 +352,34 @@ "A statically located URI."; } } } case local-well-known { leaf sbom-local-well-known { type enumeration { enum http { description "Use http (insecure) to retrieve - SBOM information."; + SBOM information. This method is NOT RECOMMENDED, + but may be unavoidable for certain classes of + deployment, where TLS has not or cannot be implemented"; } enum https { description "Use https (secure) to retrieve SBOM information."; + } enum coap { 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 { description "Use COAPS (secure) to retrieve SBOM"; } enum openc2 { description "Use OpenC2 endpoint. This is https://{host}/.well-known/openc2"; } @@ -670,48 +655,98 @@ } At this point, the management system can attempt to retrieve the SBOM, and determine which format is in use through the content-type header on the response to a GET request, independently repeat the process for vulnerability information, and apply ACLs, as appropriate. 6. Security Considerations + The YANG module specified in this document defines a schema for data + that is designed to be accessed via network management protocols such + as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer + is the secure transport layer, and the mandatory-to-implement secure + transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer + is HTTPS, and the mandatory-to-implement secure transport is TLS + [RFC8446]. + + N.B., for MUD, the mandatory method of retrieval is TLS. + + The Network Configuration Access Control Model (NACM) [RFC8341] + provides the means to restrict access for particular NETCONF or + RESTCONF users to a preconfigured subset of all available NETCONF or + RESTCONF protocol operations and content. + + There are a number of data nodes defined in this YANG module that are + writable/creatable/deletable (i.e., config true, which is the + default). These data nodes may be considered sensitive or vulnerable + in some network environments. Write operations (e.g., edit-config) + to these data nodes without proper protection can have a negative + effect on network operations. These are the subtrees and data nodes + and their sensitivity/vulnerability: + + The ietf-mud-transparency module has no operational impact on the + element itself, and is used to discover state information that may be + available on or off the element. In as much as the module itself is + made writeable, this only indicates a change in how to retrieve what + read-only elements. However, that does not mean there are no risks. + These are discussed below, and are applicable to all nodes within the + transparency container. + + If an attacker modifies the elements, they may misdirect automation + to retrieve a different set of URLs than was intended by the + designer. This in turn leads to two specific sets of risks: + + * the information retrieved would be false. + + * the URLs themselves point to malware. + + To address either risk, any change in a URL, and in particular to the + authority section, should be treated with some suspicion. One + mitigation would be to test any cloud-based URL against a reputation + service. + + Some of the readable data nodes in this YANG module may be considered + sensitive or vulnerable in some network environments. It is thus + important to control read access (e.g., via get, get-config, or + notification) to these data nodes. These are the subtrees and data + nodes and their sensitivity/vulnerability: + SBOMs provide an inventory of software. If software is available to an attacker, the attacker may well already be able to derive this very same software inventory. Manufacturers MAY restrict access to SBOM information using appropriate authorization semantics within HTTP. In particular, if a system attempts to retrieve an SBOM via HTTP and the client is not authorized, the server MUST produce an appropriate error, with instructions on how to register a particular client. One example may be to issue a certificate to the client for this purpose after a registration process has taken place. Another example would involve the use of OAUTH in combination with a federations of SBOM servers. Another risk is a skew in the SBOM listing and the actual software inventory of a device/container. For example, a manufacturer may update the SBOM on its server, but an individual device has not been upgraded yet. This may result in an incorrect policy being applied to a device. A unique mapping of a device's software version and its SBOM can minimize this risk. To further mitigate attacks against a device, manufacturers SHOULD - recommend access controls through the normal MUD mechanism. + recommend access controls. Vulnerability information is generally made available to such databases as NIST's National Vulnerability Database. It is possible that vendor may wish to release information early to some customers. We do not discuss here whether that is a good idea, but if it is - employed, then appropriate access controls and authorization would be - applied to the vulnerability resource. + employed, then appropriate access controls and authorization SHOULD + be applied to the vulnerability resource. 7. IANA Considerations 7.1. MUD Extension The IANA is requested to add "transparency" to the MUD extensions registry as follows: Extension Name: transparency Standard reference: This document @@ -749,28 +784,50 @@ 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, . + [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, + . + + [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure + Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, + . + [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . + [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF + Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, + . + [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . + [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration + Access Control Model", STD 91, RFC 8341, + DOI 10.17487/RFC8341, March 2018, + . + + [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol + Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, + . + [RFC8520] Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage Description Specification", RFC 8520, DOI 10.17487/RFC8520, March 2019, . [RFC8615] Nottingham, M., "Well-Known Uniform Resource Identifiers (URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019, . 9.2. Informative References