Prevention against this attack

[ubiratansoares]

Hi Adnan, thank you so much for this PoC and the related blog post! Super interesting!

If I got everything from your findings, could we state that a general procedure to avoid being hit by a cache poisoning attack is never restoring caches from the main branch, regardless the Workflow?

In addition, is this a vulnerability only related to actions/restore provided by Github, or would it impact any other public GHA that build on top of common actions/toolkit building blocks (eg, https://github.com/gradle/actions/blob/main/setup-gradle/action.yml )?

Thanks in advance!

[AdnaneKhan]

Hi @ubiratansoares, the correct procedure for avoiding a cache poisoning attack is to never run untrusted/unreviewed code in the context of the default branch of a repository (typically main).

This technique applies to any action that builds on top of actions/toolkit. In particular the cache hit and unzip part of it.

[ubiratansoares]

All right then! Thanks again!