CVE-2024-41949 – biscuit-auth

Package

Manager: cargo
Name: biscuit-auth
Vulnerable Version: >=4.0.0 <5.0.0

Severity

Level: Low

CVSS v3.1: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:N/I:L/A:N

CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N

EPSS: 0.00107 pctl0.29601

Details

biscuit-auth vulnerable to public key confusion in third party block Third-party blocks can be generated without transferring the whole token to the third-party authority. Instead, a `ThirdPartyBlock` request can be sent, providing only the necessary info to generate a third-party block and to sign it: - the public key of the previous block (used in the signature) - the public keys part of the token symbol table (for public key interning in datalog expressions) A third-part block request forged by a malicious user can trick the third-party authority into generating datalog trusting the wrong keypair. Consider the following example (nominal case) - Authority `A` emits the following token: `check if thirdparty("b") trusting ${pubkeyB}` - The well-behaving holder then generates a third-party block request based on the token and sends it to third-party authority `B` - Third-party `B` generates the following third-party block `thirdparty("b"); check if thirdparty("c") trusting ${pubkeyC}` - The token holder now must obtain a third-party block from third party `C` to be able to use the token Now, with a malicious user: - Authority `A` emits the following token: `check if thirdparty("b") trusting ${pubkeyB}` - The holder then attenuates the token with the following third party block `thirdparty("c")`, signed with a keypair `pubkeyD, privkeyD)` they generate - The holder then generates a third-party block request based on this token, but alter the `ThirdPartyBlockRequest` `publicKeys` field and replace `pubkeyD` with `pubkeyC` - Third-party `B` generates the following third-party block `thirdparty("b"); check if thirdparty("c") trusting ${pubkeyC}` - Due to the altered symbol table, the actual meaning of the block is `thirdparty("b"); check if thirdparty("c") trusting ${pubkeyD}` - The attacker can now use the token without obtaining a third-party block from `C`. ### Impact Tokens with third-party blocks containing `trusted` annotations generated through a third party block request

Metadata

Created: 2024-07-31T21:15:41Z
Modified: 2024-08-05T21:14:26Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/07/GHSA-p9w4-585h-g3c7/GHSA-p9w4-585h-g3c7.json
CWE IDs: ["CWE-269"]
Alternative ID: GHSA-p9w4-585h-g3c7
Finding: F159
Auto approve: 1