Guidelines for Security Considerations of RATS
draft-sardar-rats-sec-cons-04
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Author | Muhammad Usama Sardar | ||
| Last updated | 2026-07-06 | ||
| Replaces | draft-rats-sardar-sec-cons | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
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draft-sardar-rats-sec-cons-04
RATS Working Group M. U. Sardar
Internet-Draft TU Dresden
Updates: 9334 (if approved) 6 July 2026
Intended status: Informational
Expires: 7 January 2027
Guidelines for Security Considerations of RATS
draft-sardar-rats-sec-cons-04
Abstract
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. In particular, it discusses some of the 'bottom turtle'
issues. This is a work-in-progress, and the current version mainly
presents an outline of the topics that future versions will cover in
more detail.
* Corrections in published RATS RFCs
* Security concerns in two RATS drafts
* General security guidelines, baseline, or template for RATS
About This Document
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.
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/.
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on 7 January 2027.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Need for Specialized Guidance in RATS . . . . . . . . . . 3
1.2. Needs of the Target Audience of RATS . . . . . . . . . . 4
1.3. Inaccuracies in Published RATS RFCs . . . . . . . . . . . 4
1.4. Aggregator in CoServ . . . . . . . . . . . . . . . . . . 4
1.5. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4
1.5.1. Concrete Motivational Example: Practical Exploits in
Production Systems . . . . . . . . . . . . . . . . . 4
1.6. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 5
3. General Hierarchy of Authentication . . . . . . . . . . . . . 6
4. Threat Modeling . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. System Model . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Actors . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2.1. Legal perspective . . . . . . . . . . . . . . . . . . 6
4.2.2. Technical perspective . . . . . . . . . . . . . . . . 6
4.3. Threat Model . . . . . . . . . . . . . . . . . . . . . . 7
4.4. Typical Security Goals . . . . . . . . . . . . . . . . . 7
5. Attacks . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. (Evidence) Replay Attacks . . . . . . . . . . . . . . . . 7
5.2. Diversion Attacks . . . . . . . . . . . . . . . . . . . . 7
5.3. Relay Attacks . . . . . . . . . . . . . . . . . . . . . . 7
6. Potential Mitigations . . . . . . . . . . . . . . . . . . . . 8
7. Examples of Specifications That Could Be Improved . . . . . . 8
7.1. RFC9334 . . . . . . . . . . . . . . . . . . . . . . . . . 8
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7.1.1. Unprotected Evidence . . . . . . . . . . . . . . . . 8
7.1.2. Missing definitions . . . . . . . . . . . . . . . . . 8
7.1.3. Missing Roles and Conceptual Messages . . . . . . . . 9
7.2. RFC9781 . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.3. RFC9783 . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.4. RFC9711 . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.4.1. Inaccurate opinion . . . . . . . . . . . . . . . . . 9
7.4.2. Inaccurate Privacy Considerations . . . . . . . . . . 9
8. Examples of Parts of Specifications That are Detrimental for
Security . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Multi-Verifiers . . . . . . . . . . . . . . . . . . . . . 10
8.1.1. Security Considerations . . . . . . . . . . . . . . . 10
8.1.2. Privacy Considerations . . . . . . . . . . . . . . . 11
8.1.3. Open-source . . . . . . . . . . . . . . . . . . . . . 11
8.2. Aggregator-based design . . . . . . . . . . . . . . . . . 11
9. Security Considerations . . . . . . . . . . . . . . . . . . . 11
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
11.1. Normative References . . . . . . . . . . . . . . . . . . 12
11.2. Informative References . . . . . . . . . . . . . . . . . 12
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 15
History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
1.1. Need for Specialized Guidance in RATS
Every Internet Draft needs to have a "Security Considerations"
section. While general guidelines such as [RFC3552] exist, the
underlying threat model is that the endpoint is fully trusted (i.e.,
all software and hardware components in the device may access the
keys). RATS [RFC9334] has a primarily different threat model in the
sense that only parts of the endpoint (called Attester) are trusted
(i.e., only specific software and hardware components in the device
may access the keys), and the goal is to establish the
trustworthiness of the endpoint. In other words, [RFC3552] deals
with a network adversary, whereas RATS deals with an endpoint
adversary, which may have root access or physical control over the
device with which it can extract keys from software or hardware.
Moreover, remote attestation has several distinguishing features that
necessitate a separate document. One specific example of such a
feature is the architectural complexity of the endpoint. While
network protocols typically have 2 roles, RATS has additional roles,
which complicates the picture. Unfortunately, no guidelines
currently exist for remote attestation [RFC9334] in RATS. This
document aims to fill this gap.
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1.2. Needs of the Target Audience of RATS
Moreover, while the target audience of Internet Drafts is
implementers, researchers, and protocol designers
[I-D.irtf-cfrg-cryptography-specification], RATS drafts generally do
not fulfill these needs, in particular the needs of researchers and
protocol designers. On the other hand, in our observation,
implementers generally find it hard to relate the abstract concepts
of RATS to the real-world systems. In general, implementers and
protocol designers of RATS are thus left with little or no guidance.
1.3. Inaccuracies in Published RATS RFCs
Unfortunately, many published RFCs of RATS provide inaccurate or
ambiguous security and privacy considerations, which may lead to
errors in design and implementation, and give a false sense of
security. As an example, many proposed designs in [RFC9334] are
broken.
1.4. Aggregator in CoServ
RATS has recently adopted [I-D.ietf-rats-coserv], which has an
ambiguous role Aggregator, for which -- in our assessment -- the
authors have not yet provided a reasonable justification. To the
best of our knowledge and understanding, a malicious Aggregator
breaks the security of the RATS ecosystem and invalidates the formal
proofs for RATS primitives. Surprisingly, during the three-week
adoption call and one week discussion afterwards, one of the authors
of the draft [I-D.ietf-rats-coserv] did not support adoption of the
draft. Based on the above reasons, as researchers, we have genuine
skepticism about this work. We request the authors to be transparent
on this work and clarify the concerns raised at the adoption time
(summarized to some extent in this draft).
We will keep making good-faith attempts and requesting the authors to
state the risks properly.
1.5. Motivation
Unverified protocol designs, imprecisely stated threat model and
security goals have led to high and critical severity vulnerabilities
related to remote attestation.
1.5.1. Concrete Motivational Example: Practical Exploits in Production
Systems
The formal analysis led to three orthogonal issues:
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* Formal analysis [ID-Crisis-repo] found *diversion* attacks when
unique hardware identifier is not included in Evidence. For
technical details, please see the corresponding paper [ID-Crisis].
* Formal analysis [Intra-handshake.fail-repo] of several
*production* implementations of remote attestation led to the
discovery of [CVE-2026-33697] of *CVSS 7.5* for *relay* attacks.
For technical details, please see the corresponding paper
[Intra-handshake.fail].
* Further formal analysis of *production* implementation of remote
attestation has led to discovery of another class of attacks and
will potentially lead to three CVEs (currently under _responsible_
disclosure) _each_ with an expected *CVSS 9.1*.
This shows the value of precise threat model and formal analysis in
the design of secure protocols to find subtle vulnerabilities, which
could otherwise be missed. This draft aims to provide the baseline
security considerations that other drafts can simply refer to.
1.6. Scope
To improve the situation, this 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 baseline that other drafts can simply point to,
or guidelines or template that other drafts can use
2. Conventions and Definitions
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.
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3. General Hierarchy of Authentication
Authentication is a term which is often ambiguous in RATS
specifications. We propose general hierarchy of one-way
authentication [Gen-Approach], which can help precisely state the
intended level of authentication (in decreasing order):
* One-way injective agreement
* One-way non-injective agreement
* Aliveness
Recentness can be added to each of these levels of authentication.
Details will be added in future versions.
4. Threat Modeling
This section describes "What can go wrong?"
4.1. System Model
See Section 4 of [Intra-handshake.fail] as an example.
4.2. Actors
It has both legal and technical perspective.
4.2.1. Legal perspective
* 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.
4.2.2. Technical perspective
* Infrastucture Provider is a role which refers to the Processor in
GDPR. An example of this role is a cloud service provider (CSP).
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4.3. Threat Model
See Section 6.1 of [Intra-handshake.fail] as an example.
4.4. Typical Security Goals
See [ID-Crisis] as an example.
5. Attacks
Security considerations in RATS specifications need to clarify how
the following attacks are avoided or mitigated:
5.1. (Evidence) Replay Attacks
In this attack, a network or endpoint adversary -- with access to
older Evidence -- can replay Evidence with stale Claims which no
longer represent the actual state of the Attester, potentially
resulting in exposure of confidential data [RA-TLS].
Replay of stale Evidence may be within the same connection or across
multiple connections.
5.2. Diversion Attacks
In this attack, a network adversary -- with Dolev-Yao capabilities
[Dolev-Yao] and access (e.g., via Foreshadow [Foreshadow]) to the
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 [ID-Crisis].
In the context of confidential computing and TLS as a transport
protocol, we reported these attacks to the TLS WG in February 2025
[Usama-TLS-26Feb25]. A formal proof is available [ID-Crisis-repo]
for further research and development. Since reporting to TLS WG,
these attacks have been practically exploited in TEE.fail
(https://tee.fail/), Wiretap.fail (https://wiretap.fail/), and BadRAM
(https://badram.eu/).
5.3. Relay Attacks
In this attack, a network or endpoint adversary -- with access to
suitable binding material -- can relay an attestation request to a
genuine Attester and present the genuine Evidence as its own,
potentially resulting in impersonation of genuine Attester
[Intra-handshake.fail].
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Note that _replay_ is about _same_ Attester while _relay_ attack is
about _different_ Attesters.
6. Potential Mitigations
This section describes the countermeasures and their evaluation.
To mitigate the above attacks, we propose post-handshake attestation.
We are not aware of any attacks on post-handshake attestation. Post-
handshake attestation avoids replay attacks by using a fresh
attestation nonce. Moreover, considering TLS as the transport
protocol, it avoids diversion and relay attacks by binding the
Evidence to the underlying TLS connection, such as using Exported
Keying Material (EKM) [I-D.ietf-tls-rfc8446bis], as proposed in
Section 9.2 of [ID-Crisis]. [RFC9261] and [RFC9266] provide
mechanisms for such bindings. Efforts for a formal proof of security
of post-handshake attestation are ongoing.
7. Examples of Specifications That Could Be Improved
7.1. RFC9334
7.1.1. Unprotected Evidence
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.
7.1.2. Missing definitions
[RFC9334] uses the term Conceptual Messages in capitalization without
proper definition.
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7.1.3. Missing Roles and Conceptual Messages
* 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].
7.2. RFC9781
As argued above for RFC9334, security considerations in [RFC9781] are
essentially insufficient.
7.3. RFC9783
[RFC9783] uses:
* 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
7.4. RFC9711
7.4.1. Inaccurate opinion
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].
7.4.2. Inaccurate Privacy Considerations
Section 8.4 of [RFC9711] has:
| The nonce claim is based on a value usually derived remotely
| (outside of the entity).
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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).
8. Examples of Parts of Specifications That are Detrimental for
Security
We believe that the following parts of designs are detrimental for
the RATS ecosystem and without proper security and privacy
considerations, they put the community at risk.
8.1. Multi-Verifiers
We believe this draft [I-D.deshpande-rats-multi-verifier] in its
current form is doing *disservice* to the community by substantially
degrading *both* the security and privacy of the systems, and not
properly highlighting the security and privacy risks, and by
implicitly promoting the blind trust in vendors.
In summary:
* From a security perspective, if one of the Verifiers breaks, it
breaks the whole system.
* From a privacy perspective, the current design also exposes
Personally Identifiable Information (PII) to all the Verifiers.
8.1.1. Security Considerations
What's important from the security standpoint is the TCB of the RP,
and not the Attester. This is because it is the RP who has to make
final trust decision, and not the Attester. Verifier is -- in any
case -- in the TCB of RP.
Say there are two Verifiers; how do they establish trust with each
other? Who verifies the Verifier - Verifier attested TLS?
Section 7.2 of [I-D.deshpande-rats-multi-verifier] falls apart on
this.
Hence, we believe the security considerations of multi-verifiers
[I-D.deshpande-rats-multi-verifier] must say:
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Compared to a single verifier, the use of multi-verifiers increases
security risks in terms of increasing the overall Trusted Computing
Base (TCB) from the RP's perspective.
8.1.2. Privacy Considerations
In addition to revealing the PII to the Lead Verifier (which say is
kind of equivalent to monolithic verifier), the current proposal in
draft reveals the PII to all those Component Verifiers as well.
We believe the privacy considerations of multi-verifiers
[I-D.deshpande-rats-multi-verifier] must say:
Compared to a single verifier, the use of multi-verifiers may
increase the privacy risks, as potentially sensitive information may
be sent to multiple verifiers.
8.1.3. Open-source
Besides, the rationale presented by the authors at meeting 124 --
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.
8.2. Aggregator-based design
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 Providers 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 Providers and Endorsers. That is, even if Reference Values
Providers 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.
9. Security Considerations
All of this document is about security considerations.
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10. IANA Considerations
This document has no IANA actions.
11. References
11.1. 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/rfc/rfc2119>.
[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/rfc/rfc8174>.
[RFC9334] Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
W. Pan, "Remote ATtestation procedureS (RATS)
Architecture", RFC 9334, DOI 10.17487/RFC9334, January
2023, <https://www.rfc-editor.org/rfc/rfc9334>.
[RFC9711] Lundblade, L., Mandyam, G., O'Donoghue, J., and C.
Wallace, "The Entity Attestation Token (EAT)", RFC 9711,
DOI 10.17487/RFC9711, April 2025,
<https://www.rfc-editor.org/rfc/rfc9711>.
[RFC9781] Birkholz, H., O'Donoghue, J., Cam-Winget, N., and C.
Bormann, "A Concise Binary Object Representation (CBOR)
Tag for Unprotected CBOR Web Token Claims Sets (UCCS)",
RFC 9781, DOI 10.17487/RFC9781, May 2025,
<https://www.rfc-editor.org/rfc/rfc9781>.
[RFC9783] Tschofenig, H., Frost, S., Brossard, M., Shaw, A., and T.
Fossati, "Arm's Platform Security Architecture (PSA)
Attestation Token", RFC 9783, DOI 10.17487/RFC9783, June
2025, <https://www.rfc-editor.org/rfc/rfc9783>.
11.2. Informative References
[Clarifications-EAT]
Sardar, M. U., "Clarifications in draft-ietf-rats-eat",
April 2025, <https://mailarchive.ietf.org/arch/msg/
rats/4V2zZHhk5IuxwcUMNWpPBpnzpaM/>.
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[CVE-2026-33697]
CVE, "CoCoS attested TLS is vulnerable to relay attacks
via extracted ephemeral TLS keys", March 2026,
<https://www.cve.org/CVERecord?id=CVE-2026-33697>.
[Dolev-Yao]
Dolev, D. and A. Yao, "On the security of public key
protocols", March 1983.
[Foreshadow]
Jo Van Bulck, Marina Minkin, Ofir Weisse, Daniel Genkin,
Baris Kasikci, Frank Piessens, Mark Silberstein, Thomas F
Wenisch, Yuval Yarom, and Raoul Strackx, "Foreshadow",
October 2025, <https://foreshadowattack.eu/>.
[GDPR] European Commission, "Regulation (EU) 2016/679 of the
European Parliament and of the Council of 27 April 2016 on
the protection of natural persons with regard to the
processing of personal data and on the free movement of
such data, and repealing Directive 95/46/EC (General Data
Protection Regulation) (Text with EEA relevance)", May
2016, <https://eur-lex.europa.eu/eli/reg/2016/679/oj>.
[Gen-Approach]
Sardar, M. U., "Perspicuity of Attestation Mechanisms in
Confidential Computing: General Approach", October 2025,
<https://www.researchgate.net/
publication/396593308_Perspicuity_of_Attestation_Mechanisms_in_Confidential_Computing_General_Approach>.
[I-D.deshpande-rats-multi-verifier]
Deshpande, Y., jun, Z., Labiod, H., and H. Birkholz,
"Remote Attestation with Multiple Verifiers", Work in
Progress, Internet-Draft, draft-deshpande-rats-multi-
verifier-04, 7 February 2026,
<https://datatracker.ietf.org/doc/html/draft-deshpande-
rats-multi-verifier-04>.
[I-D.ietf-rats-coserv]
Howard, P., Fossati, T., Birkholz, H., Kamal, S., Mandyam,
G., and D. Ma, "Concise Selector for Endorsements and
Reference Values", Work in Progress, Internet-Draft,
draft-ietf-rats-coserv-07, 6 July 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-rats-
coserv-07>.
[I-D.ietf-tls-rfc8446bis]
Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", Work in Progress, Internet-Draft, draft-
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ietf-tls-rfc8446bis-14, 13 September 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-tls-
rfc8446bis-14>.
[I-D.irtf-cfrg-cryptography-specification]
Sullivan, N. and C. A. Wood, "Guidelines for Writing
Cryptography Specifications", Work in Progress, Internet-
Draft, draft-irtf-cfrg-cryptography-specification-02, 7
July 2025, <https://datatracker.ietf.org/doc/html/draft-
irtf-cfrg-cryptography-specification-02>.
[ID-Crisis]
Sardar, M., Moustafa, M., and T. Aura, "Identity Crisis in
Confidential Computing: Formal Analysis of Attested TLS",
ACM, Proceedings of the ACM Asia Conference on Computer
and Communications Security pp. 547-560,
DOI 10.1145/3779208.3785387, June 2026,
<https://doi.org/10.1145/3779208.3785387>.
[ID-Crisis-repo]
Sardar, M. U., Moustafa, M., and T. Aura, "Identity Crisis
in Confidential Computing: Formal Analysis of Attested
TLS", November 2025, <https://github.com/CCC-Attestation/
formal-spec-id-crisis>.
[Intra-handshake.fail]
Sardar, M. U., Dubeyko, V., and J.-M. Jacquet, "Intra-
handshake.fail (CVE-2026-33697): High-severity CVE in
Attested TLS", June 2026, <https://www.researchgate.net/
publication/408219182_Intra-handshakefail_CVE-2026-
33697_High-severity_CVE_in_Attested_TLS>.
[Intra-handshake.fail-repo]
Sardar, M. U., Dubeyko, V., and J.-M. Jacquet, "Intra-
handshake.fail (CVE-2026-33697): High-severity CVE in
Attested TLS", June 2026,
<https://github.com/CCC-Attestation/formal-spec-KBS>.
[RA-TLS] Sardar, M., Niemi, A., Tschofenig, H., and T. Fossati,
"Towards Validation of TLS 1.3 Formal Model and
Vulnerabilities in Intel’s RA-TLS Protocol", Institute of
Electrical and Electronics Engineers (IEEE), IEEE
Access vol. 12, pp. 173670-173685,
DOI 10.1109/access.2024.3497184, 2024,
<https://doi.org/10.1109/access.2024.3497184>.
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[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
DOI 10.17487/RFC3552, July 2003,
<https://www.rfc-editor.org/rfc/rfc3552>.
[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/rfc/rfc8446>.
[RFC9261] Sullivan, N., "Exported Authenticators in TLS", RFC 9261,
DOI 10.17487/RFC9261, July 2022,
<https://www.rfc-editor.org/rfc/rfc9261>.
[RFC9266] Whited, S., "Channel Bindings for TLS 1.3", RFC 9266,
DOI 10.17487/RFC9266, July 2022,
<https://www.rfc-editor.org/rfc/rfc9266>.
[Sec-Cons-RATS]
Sardar, M. U., "Security considerations of remote
attestation (RFC9334)", November 2024,
<https://mailarchive.ietf.org/arch/msg/rats/
jcAv9FKbYSIVtUNQ8ggEHL8lrmM/>.
[Tech-Concepts]
Sardar, M. U., "Perspicuity of Attestation Mechanisms in
Confidential Computing: Technical Concepts", October 2025,
<https://www.researchgate.net/
publication/396199290_Perspicuity_of_Attestation_Mechanisms_in_Confidential_Computing_Technical_Concepts>.
[Usama-TLS-26Feb25]
Muhammad Usama Sardar, "Impersonation attacks on protocol
in draft-fossati-tls-attestation (Identity crisis in
Attested TLS) for Confidential Computing", February 2025,
<https://mailarchive.ietf.org/arch/msg/tls/
Jx_yPoYWMIKaqXmPsytKZBDq23o/>.
Acknowledgments
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.
History
-01
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* Concrete text proposal for security and privacy considerations of
multi-verifiers [I-D.deshpande-rats-multi-verifier]
-02
* Introduction and motivation
* Defined replay and relay attacks
* Added mitigations
Author's Address
Muhammad Usama Sardar
TU Dresden
Email: muhammad_usama.sardar@tu-dresden.de
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