Credential disclosure in syft when SYFT_ATTEST_PASSWORD environment variable set

A password disclosure flaw was found in Syft versions v0.69.0 and v0.69.1. This flaw leaks the password stored in the SYFT_ATTEST_PASSWORD environment variable.

Impact

The SYFT_ATTEST_PASSWORD environment variable is for the syft attest command to generate attested SBOMs for the given container image. This environment variable is used to decrypt the private key (provided with syft attest --key <path-to-key-file>) during the signing process while generating an SBOM attestation.

This vulnerability affects users running syft that have the SYFT_ATTEST_PASSWORD environment variable set with credentials (regardless of if the attest command is being used or not). Users that do not have the environment variable SYFT_ATTEST_PASSWORD set are not affected by this issue.

The credentials are leaked in two ways:
- in the syft logs when -vv or -vvv are used in the syft command (which is any log level >= DEBUG)
- in the attestation or SBOM only when the syft-json format is used

Note that as of v0.69.0 any generated attestations by the syft attest command are uploaded to the OCI registry (if you have write access to that registry) in the same way cosign attach is done. This means that any attestations generated for the affected versions of syft when the SYFT_ATTEST_PASSWORD environment variable was set would leak credentials in the attestation payload uploaded to the OCI registry.

Example commands run from affected versions of syft that show the credential disclosure:

$ SYFT_ATTEST_PASSWORD=123456 syft <container-image-or-directory-input> -o syft-json | grep 123456
# "123456" is in the output

$ SYFT_ATTEST_PASSWORD=123456 syft attest <container-image-input> -o syft-json 
$ cosign download attestation <container-image-input> | jq -r '.payload' | base64 -d | grep 123456
# "123456" is in the output

Patches

The patch has been released in v0.70.0.

Workarounds

There are no workarounds for this vulnerability.

References

Patch pull request: https://github.com/anchore/syft/pull/1538