malcontent OCI image pull credential exfiltration via malicious registry token realm

Malcontent could be made to expose Docker registry credentials if it scanned a specially crafted OCI image reference. Malcontent uses google/go-containerregistry for OCI image pulls, which by default uses the Docker credential keychain. A malicious registry could return a WWW-Authenticate header redirecting token authentication to an attacker-controlled endpoint, causing credentials to be sent to that endpoint.

Fix: Default to anonymous auth for OCI pulls

Acknowledgements

Thank you to Oleh Konko from 1seal for discovering and reporting this issue.