Sigstore Java

sigstore-java is a sigstore java client for interacting with sigstore infrastructure. sigstore-java has insufficient verification for a situation where a bundle provides a invalid signature for a checkpoint. This bug impacts clients using any variation of KeylessVerifier.verify(). Currently checkpoints are only used to ensure the root hash of an inclusion proof was provided by the log in question. Failing to validate that means a bundle may provide an inclusion proof that doesn't actually correspond to the log in question. This may eventually lead a monitor/witness being unable to detect when a compromised logs are providing different views of themselves to different clients. There are other mechanisms right now that mitigate this, such as the signed entry timestamp. Sigstore-java currently requires a valid signed entry timestamp. By correctly verifying the signed entry timestamp we can make certain assertions about the log signing the log entry (like the log was aware of the artifact signing event and signed it). Therefore the impact on clients that are not monitors/witnesses is very low. This vulnerability is fixed in 1.2.0.

Published: 2024-12-05T22:08:37.195Z
Updated: 2024-12-10T14:55:08.151Z

sigstore-java is a sigstore java client for interacting with sigstore infrastructure. sigstore-java has insufficient verification for a situation where a validly-signed but "mismatched" bundle is presented as proof of inclusion into a transparency log. This bug impacts clients using any variation of KeylessVerifier.verify(). The verifier may accept a bundle with an unrelated log entry, cryptographically verifying everything but fails to ensure the log entry applies to the artifact in question, thereby "verifying" a bundle without any proof the signing event was logged. This allows the creation of a bundle without fulcio certificate and private key combined with an unrelated but time-correct log entry to fake logging of a signing event. A malicious actor using a compromised identity may want to do this to prevent discovery via rekor's log monitors. The signer's identity will still be available to the verifier. The signature on the bundle must still be on the correct artifact for the verifier to pass. sigstore-gradle-plugin and sigstore-maven-plugin are not affected by this as they only provide signing functionality. This issue has been patched in v1.1.0 release with PR #856. All users are advised to upgrade. There are no known workarounds for this vulnerability.

Published: 2024-11-26T18:41:29.240Z
Updated: 2024-11-26T19:46:41.263Z