go-witness Improper Verification of AWS EC2 Identity Documents

Open Source Vulnerabilities GHSA-72c7-4g63-hpw5

### Impact This vulnerability only affects users of the AWS attestor. Users of the AWS attestor could have unknowingly received a forged identity document. While this may seem unlikely, AWS recently issued a security bulletin about IMDS (Instance Metadata Service) impersonation.[^1] There are multiple locations where the verification of the identity document will mistakenly report a successful verification. - If a signature is not present or is empty https://github.com/in-toto/go-witness/blob/0c8bb30c143951d88b1d4b32f260c5f67d30137b/attestation/aws-iid/aws-iid.go#L161-L163 - If the RSA verification of the document fails for any reason https://github.com/in-toto/go-witness/blob/0c8bb30c143951d88b1d4b32f260c5f67d30137b/attestation/aws-iid/aws-iid.go#L192-L196 ### Workarounds The contents of the AWS attestation contain the identity document, signature, and public key that was used to verify the document. These attestations and their could be identity documents could be manually verified with the `openssl` command line as documented in the below reference from AWS.[^2] However, the certificate containing the public key was hard-coded into the attestor. https://github.com/in-toto/go-witness/blob/0c8bb30c143951d88b1d4b32f260c5f67d30137b/attestation/aws-iid/aws-iid.go#L46-L66 Since the original authoring of the attestor, AWS has moved to region specific public certificates. The currently valid certificates were issued around April of 2024, making the identification of attestations with forged content difficult without additional trusted data proving the AWS region in which the attestation was created. ### Patches This vulnerability is addressed in `go-witness` 0.9.1 and `witness` 0.10.1. ### Resources [^1]: [AWS Security Bulletin on IMDS Impersonation](https://aws.amazon.com/security/security-bulletins/rss/aws-2025-021/) [^2]: [Verification of instance identity documents](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/verify-iid.html#verify-signature)

Open Source Vulnerabilities GO-2025-4028

go-witness is Vulnerable to Improper Verification of AWS EC2 Identity Documents in github.com/in-toto/go-witness

Open Source Vulnerabilities CVE-2025-62375

go-witness and witness are Go modules for generating attestations. In go-witness versions 0.8.6 and earlier and witness versions 0.9.2 and earlier the AWS attestor improperly verifies AWS EC2 instance identity documents. Verification can incorrectly succeed when a signature is not present or is empty, and when RSA signature verification fails. The attestor also embeds a single legacy global AWS public certificate and does not account for newer region specific certificates issued in 2024, making detection of forged documents difficult without additional trusted region data. An attacker able to supply or intercept instance identity document data (such as through Instance Metadata Service impersonation) can cause a forged identity document to be accepted, leading to incorrect trust decisions based on the attestation. This is fixed in go-witness 0.9.1 and witness 0.10.1. As a workaround, manually verify the included identity document, signature, and public key with standard tools (for example openssl) following AWS’s verification guidance, or disable use of the AWS attestor until upgraded.