| Internet-Draft | RATS Security Considerations | November 2025 |
| Sardar | Expires 31 May 2026 | [Page] |
This document aims to provide guidelines and best practices for writing security considerations for technical specifications for RATS targeting the needs of implementers, researchers, and protocol designers. The current version presents an outline of the topics that future versions will cover in more detail.¶
This note is to be removed before publishing as an RFC.¶
The latest revision of this draft can be found at https://muhammad-usama-sardar.github.io/rats-sec-cons/draft-sardar-rats-sec-cons.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-sardar-rats-sec-cons/.¶
Source for this draft and an issue tracker can be found at https://github.com/muhammad-usama-sardar/rats-sec-cons.¶
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While excellent guidelines such as [I-D.irtf-cfrg-cryptography-specification] exist, remote attestation [RFC9334] has several distinguishing features which necessitate a separate document. One specific example of such a feature is architectural complexity.¶
The draft presents an outline of three topics that future versions will cover in more detail:¶
Corrections in published RATS RFCs [RFC9334], [RFC9781], [RFC9783] and [RFC9711]¶
Security concerns in one currently adopted RATS draft [I-D.ietf-rats-coserv] and one proposed for adoption RATS draft [I-D.deshpande-rats-multi-verifier]¶
General security guidelines, baseline or template that other drafts can simply point to¶
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.¶
[Gen-Approach] proposes general hierarchy of one-way authentication, which can help precisely state the intended level of authentication (in decreasing order):¶
Recentness can be added to each of these levels of authentication. Details will be added in future versions.¶
This section describes "What can go wrong?" TODO.¶
TODO.¶
TODO.¶
Data subject is an identifiable natural person (as defined in Article 4 (1) of GDPR [GDPR]).¶
(Data) Controller (as defined in Article 4 (7) of GDPR [GDPR]) manages and controls what happens with personal data of data subject.¶
(Data) Processor (as defined in Article 4 (8) of GDPR [GDPR]) performs data processing on behalf of the data controller.¶
TODO.¶
Infrastucture Provider is a role which refers to the Processor in GDPR. An example of this role is a cloud service provider (CSP).¶
TODO.¶
TODO.¶
TODO.¶
Security considerations in RATS specifications need to clarify how the following attacks are avoided or mitigated:¶
See [Meeting-124-RATS-Slides]. TODO.¶
See [Meeting-124-RATS-Slides]. TODO.¶
In this attack, a network adversary -- with Dolev-Yao capabilities [Dolev-Yao] and access (e.g., via Foreshadow [Foreshadow]) to attestation key of any machine in the world -- can redirect a connection intended for a specific Infrastructure Provider to the compromised machine, potentially resulting in exposure of confidential data [Meeting-122-TLS-Slides]. TODO.¶
This section will describe the countermeasures and their evaluation. See [Meeting-124-RATS-Slides]. TODO.¶
Section 7.4 of [RFC9334] has:¶
A conveyance protocol that provides authentication and integrity protection can be used to convey Evidence that is otherwise unprotected (e.g., not signed).¶
Using a conveyance protocol that provides authentication and integrity protection, such as TLS 1.3 [RFC8446], to convey Evidence that is otherwise unprotected (e.g., not signed) undermines all security of remote attestation. Essentially, this breaks the chain up to the trust anchor (such as hardware manufacturer) for remote attestation. Hence, remote attestation effectively provides no protection in this case and the security guarantees are limited to those of the conveyance protocol only. In order to benefit from remote attestation, Evidence MUST be protected using dedicated keys chaining back to the trust anchor for remote attestation.¶
[RFC9334] uses the term Conceptual Messages in capitalization without proper definition.¶
Identity Supplier and its corresponding conceptual message Identity are missing and need to be added to the architecture [Tech-Concepts].¶
Attestation Challenge as conceptual message needs to be added to the architecture [Tech-Concepts].¶
As argued above for RFC9334, security considerations in [RFC9781] are essentially insufficient.¶
3x epoch handle (with reference to Section 10.2 of [RFC9334] and Section 10.3 of [RFC9334]) whereas RFC9334 never uses epoch handle at all!¶
1x epoch ID with no reference and no explanation of how it is different from epoch handle¶
Section 7.4 of [RFC9711] has:¶
For attestation, the keys are associated with specific devices and are configured by device manufacturers.¶
The quoted text is inaccurate and just an opinion of the editors. It should preferably be removed from the RFC. For example, in SGX, the keys are not configured by the manufacturer alone. The platform owner can provide a random value called OWNER_EPOCH.¶
For technical details and proposed text, see [Clarifications-EAT].¶
Section 8.4 of [RFC9711] has:¶
The nonce claim is based on a value usually derived remotely (outside of the entity).¶
Attester-generated nonce does not provide any replay protection since the Attester can pre-generate an Evidence that might not reflect the actual system state, but a past one.¶
See the attack trace for Attester-generated nonce at [Sec-Cons-RATS].¶
For replay protection, nonce should always be derived remotely (for example, by the Relying Party).¶
We believe that the following parts of designs are detrimental for the RATS ecosystem:¶
The design of multi-verifiers [I-D.deshpande-rats-multi-verifier] not only increases security risks in terms of increasing the Trusted Computing Base (TCB), but also increases the privacy risks, as potentially sensitive information is sent to multiple verifiers.¶
Besides, the rationale presented by the authors -- appraisal policy being the intellectual property of the vendors -- breaks the open-source nature of RATS ecosystem. This requires blindly trusting the vendors and increases the attack surface.¶
Aggregator in [I-D.ietf-rats-coserv] is an explicit trust anchor and the addition of new trust anchor needs to have a strong justification. Having a malicious Aggregator in the design trivially breaks all the guarantees. It should be clarified how trust is established between Aggregator and Verifier in the context of Confidential Computing threat model.¶
The fact that Aggregator has collective information of Reference Values Provider and Endorsers makes it a special target of attack, and thus a single point of failure. It increases security risks because Aggregator can be compromised independent of the Reference Values Provider and Endorsers. That is, even if Reference Values Provider and Endorsers are secure, the compromise of Aggregator breaks the security of the system. Moreover, if Aggregator is not running inside a TEE, it is relatively easy to compromise the secrets.¶
All of this document is about security considerations.¶
This document has no IANA actions.¶
The author wishes to thank Ira McDonald and Ivan Gudymenko for insightful discussions. The author also wishes to thank the authors of [I-D.ietf-rats-coserv] (in particular Thomas Fossati and Paul Howard) for several discussions, which unfortunately could not resolve the above concerns, and hence led to this draft. The author also gratefully acknowledges the authors of [I-D.irtf-cfrg-cryptography-specification], which serves as the inspiration of this work.¶