Unlinkability broken in ursa when verifiers use malicious keys
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: poc
- Automatable: no
- Technical impact: partial
Summary
Ursa is a cryptographic library for use with blockchains. A weakness in the Hyperledger AnonCreds specification that is not mitigated in the Ursa and AnonCreds implementations is that the Issuer does not publish a key correctness proof demonstrating that a generated private key is sufficient to meet the unlinkability guarantees of AnonCreds. The Ursa and AnonCreds CL-Signatures implementations always generate a sufficient private key. A malicious issuer could in theory create a custom CL Signature implementation (derived from the Ursa or AnonCreds CL-Signatures implementations) that uses weakened private keys such that presentations from holders could be shared by verifiers to the issuer who could determine the holder to which the credential was issued. This vulnerability could impact holders of AnonCreds credentials implemented using the CL-signature scheme in the Ursa and AnonCreds implementations of CL Signatures. The ursa project has has moved to end-of-life status and no fix is expected.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: poc · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- hyperledger ursa
through 0.3.7
- anoncreds-clsignaturescrates.io
All versions
- ursacrates.io
through 0.3.7