Internet-Draft JOSE: Deprecate 'none' and 'RSA1_5' September 2024
Madden Expires 16 March 2025 [Page]
Workgroup:
Javascript Object Signing and Encryption
Internet-Draft:
draft-madden-jose-deprecate-none-rsa15-01
Updates:
7518 (if approved)
Published:
Intended Status:
Standards Track
Expires:
Author:
N. Madden
Illuminated Security Ltd

JOSE: Deprecate 'none' and 'RSA1_5'

Abstract

This draft updates [RFC7518] to deprecate the JWS algorithm "none" and the JWE algorithm "RSA1_5". These algorithms have known security weaknesses.

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://NeilMadden.github.io/jose-deprecate-none-rsa1_5/draft-madden-jose-deprecate-none-rsa15.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-madden-jose-deprecate-none-rsa15/.

Discussion of this document takes place on the Javascript Object Signing and Encryption Working Group mailing list (mailto:jose@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/jose/. Subscribe at https://www.ietf.org/mailman/listinfo/jose/.

Source for this draft and an issue tracker can be found at https://github.com/NeilMadden/jose-deprecate-none-rsa1_5.

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 16 March 2025.

Table of Contents

1. Introduction

JSON Web Algorithms (JWA, [RFC7518]) introduced several standard algorithms for both JSON Web Signature (JWS) and JSON Web Encryption (JWE). Many of these algorithms have stood the test of time and are still in widespread use. However, some algorithms have proved to be difficult to implement correctly leading to exploitable vulnerabilities. This draft deprecates two such algorithms:

1.1. The 'none' algorithm

The "none" algorithm creates an Unsecured JWS, whose contents are completely unsecured as the name implies. Despite strong guidance in the original RFC around not accepting Unsecured JWS by default, many implementations have had serious bugs due to accepting this algorithm. In some cases, this has led to a complete loss of security as authenticity and integrity checking can be disabled by an adversary simply by changing the algorithm ("alg") header in the JWS. The website [howmanydays] tracks public vulnerabilities due to implementations mistakenly accepting the "none" algorithm. It currently lists 12 reports, many of which have high impact ratings. The following is a partial list of issues known to have been caused by misuse of the "none" algorithm, with a Common Vulnerability Enumeration [CVE] identifier, and a Common Vulnerability Scoring System [CVSS] score indicating the severity of the impact:

Many other vulnerabilities have been reported without an accompanying CVE, which we do not list here.

Although there are some legitimate use-cases for Unsecured JWS, these are relatively few in number and can easily be satisfied by alternative means. The small risk of breaking some of these use-cases is far outweighed by the improvement in security for the majority of JWS users who may be impacted by accidental acceptance of the "none" algorithm.

1.2. The 'RSA1_5' algorithm

The "RSA1_5" algorithm implements RSA encryption using PKCS#1 version 1.5 padding [RFC8017]. This padding mode has long been known to have security issues, since at least Bleichenbacher's attack in 1998. It was supported in JWE due to the wide deployment of this algorithm, especially in legacy hardware. However, more secure replacements such as OAEP [RFC8017] or elliptic curve encryption algorithms are now widely available. NIST has disallowed the use of this encryption mode for federal use since the end of 2023 [NIST.SP800-131r2] and a CFRG draft [I-D.kario-rsa-guidance] also deprecates this encryption mode for IETF protocols. This document therefore also deprecates this algorithm for JWE.

1.3. Guidance on deprecation

Both of the algorithms listed above are deprecated for use in JWS and JWE. JOSE library developers SHOULD deprecate support for these algorithms and commit to a timeline for removal. Application developers SHOULD disable support for these algorithms by default. New specifications building on top of JOSE MUST NOT allow the use of either algorithm.

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.

3. Security Considerations

No security issues are introduced by this specification.

4. IANA Considerations

4.1. JOSE Algorithm Deprecations

The following changes are to be made to the IANA JOSE Web Signature and Encryption Algorithms registry:

  • For the entry with Algorithm Name "none", update the JOSE Implementation Requirements to "Deprecated".

  • For the entry with Algorithm Name "RSA1_5", update the JOSE Implementation Requirements to "Deprecated".

4.2. Updated Review Instructions for Designated Experts

The review instructions for the designated experts for the IANA "JSON Web Signature and Encryption Algorithms" registry [IANA.JOSE.Algorithms] in Section 7.1 of [RFC7518] are updated to add this additional review criteria:

  • For JWS signature algorithms, only algorithms that meet the standard security goal of existential unforgeability under a chosen message attack (EUF-CMA) should be considered for approval.

  • For JWE key management algorithms (specified with the "alg" header), only algorithms that meet the standard security goal of indistinguishability under an adaptive chosen ciphertext attack (IND-CCA2) should be considered for approval.

  • For JWE content encryption methods (specified with the "enc" header), only algorithms that meet the standard security goal of authenticated encryption with associated data (AEAD) should be considered for approval.

5. References

5.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC7518]
Jones, M., "JSON Web Algorithms (JWA)", RFC 7518, DOI 10.17487/RFC7518, , <https://www.rfc-editor.org/rfc/rfc7518>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/rfc/rfc8174>.

5.2. Informative References

[CVE]
MITRE, "Common Vulnerability Enumeration Database", n.d., <https://cve.mitre.org>.
[CVSS]
FIRST, "Common Vulnerability Scoring System", n.d., <https://www.first.org/cvss/>.
[howmanydays]
Sanderson, J., "How Many Days Has It Been Since a JWT alg:none Vulnerability?", , <https://github.com/zofrex/howmanydayssinceajwtalgnonevuln/blob/deploy/data/vulns.yml>.
[I-D.kario-rsa-guidance]
Kario, A., "Implementation Guidance for the PKCS #1 RSA Cryptography Specification", Work in Progress, Internet-Draft, draft-kario-rsa-guidance-02, , <https://datatracker.ietf.org/doc/html/draft-kario-rsa-guidance-02>.
[IANA.JOSE.Algorithms]
IANA, "JOSE Algorithms", n.d., <https://www.iana.org/assignments/jose/jose.xhtml#web-signature-encryption-algorithms>.
[NIST.SP800-131r2]
Barker, E. and A. Roginsky, "NIST SP 800-131A Rev. 2: Transitioning the Use of Cryptographic Algorithms and Key Lengths", , <https://csrc.nist.gov/pubs/sp/800/131/a/r2/final>.
[RFC8017]
Moriarty, K., Ed., Kaliski, B., Jonsson, J., and A. Rusch, "PKCS #1: RSA Cryptography Specifications Version 2.2", RFC 8017, DOI 10.17487/RFC8017, , <https://www.rfc-editor.org/rfc/rfc8017>.

Acknowledgments

Author's Address

Neil Madden
Illuminated Security Ltd