Steve doesn’t verify a server’s certificate and is susceptible to man-in-the-middle (MitM) attacks

Impact

A vulnerability has been identified in Steve where by default it was using an insecure option that did not validate the certificate presented by the remote server while performing a TLS connection. This could allow the execution of a man-in-the-middle (MitM) attack against services using Steve.

For example, Rancher relies on Steve as a dependency for its user interface (UI) to proxy requests to Kubernetes clusters. Users who have the permission to create a service in Rancher’s local cluster can take over Rancher’s UI and display their own UI to gather sensitive information. This is only possible when the setting ui-offline-preferred is manually set to remote (by default Rancher sets it to dynamic). This enables further attacks such as cross-site scripting (XSS), or tampering the UI to collect passwords from other users etc.

Please consult the associated MITRE ATT&CK - Technique - Adversary-in-the-Middle for further information about this category of attack.

Patches

Patched versions of Steve include releases v0.2.1, v0.3.3, v0.4.4 and v0.5.13.

This vulnerability is addressed by changing Steve to always verify a server’s certificate based on Go’s TLS settings.

Workarounds

If you can't upgrade to a fixed version, please make sure that you are only using Steve to connect to trusted servers.

References

If you have any questions or comments about this advisory: - Reach out to the SUSE Rancher Security team for security related inquiries. - Open an issue in the Rancher repository. - Verify with our support matrix and product support lifecycle.