CVE-2022-23649 Information

Description

Cosign provides container signing verification and storage in an OCI registry for the sigstore project. Prior to version 1.5.2 Cosign can be manipulated to claim that an entry for a signature exists in the Rekor transparency log even if it doesn’t. This requires the attacker to have pull and push permissions for the signature in OCI. This can happen with both standard signing with a keypair and \keyless signing\ with Fulcio. If an attacker has access to the signature in OCI they can manipulate cosign into believing the entry was stored in Rekor even though it wasn’t. The vulnerability has been patched in v1.5.2 of Cosign. The signature in the signedEntryTimestamp provided by Rekor is now compared to the signature that is being verified. If these don’t match then an error is returned. If a valid bundle is copied to a different signature verification should fail. Cosign output now only informs the user that certificates were verified if a certificate was in fact verified. There is currently no known workaround.

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Reference

https://github.com/sigstore/cosign/security/advisories/GHSA-ccxc-vr6p-4858 https://github.com/sigstore/cosign/commit/96d410a6580e4e81d24d112a0855c70ca3fb5b49

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

LOW

Base Score

NONE

Base Severity

3.3