Biscuit is an authorization token with decentralized verification, offline attenuation and strong security policy enforcement based on a logic language. 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: 1. the public key of the previous block (used in the signature), 2. 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. Tokens with third-party blocks containing `trusted` annotations generated through a third party block request. This has been addressed in version 4 of the specification. Users are advised to update their implementations to conform. There are no known workarounds for this vulnerability.
Metrics
CVSS Version: 3.1 |
Base Score: 3 LOW Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:N/I:L/A:N
l➤ Exploitability Metrics: Attack Vector (AV)* NETWORK Attack Complexity (AC)* HIGH Privileges Required (PR)* HIGH User Interaction (UI)* NONE Scope (S)* CHANGED