Impact

Due to incorrect use of a default URL, singularity action commands (run/shell/exec) specifying a container using a library:// URI will always attempt to retrieve the container from the default remote endpoint (cloud.sylabs.io) rather than the configured remote endpoint.

An attacker may be able to push a malicious container to the default remote endpoint with a URI that is identical to the URI used by a victim with a non-default remote endpoint, thus executing the malicious container.

Only action commands (run/shell/exec) against library:// URIs are affected. Other commands such as pull / push respect the configured remote endpoint.

Patches

All users should upgrade to Singularity 3.7.4 or later.

Workarounds

Users who only interact with the default remote endpoint or do not use the library:// url are not affected.

Installations with an execution control list configured to restrict execution to containers signed with specific secure keys are not affected.

Acknowledgements

This issue was found by Mike Frisch and brought to our attention by Sylabs. Sylabs is making a coordinated disclosure.

For more information

General questions about the impact of the advisory can be asked in the:

Singularity Slack Channel Singularity Mailing List Any sensitive security concerns should be directed to: [email protected]