Lack of "lock file" for Github actions is making the ecosystem vulnerable to supply chain attacks

[MarkusSintonen]

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It is terrible that Github actions do not support "lock file" mechanism for locking the chain of action dependencies. Any decent dependency managers support "lock file" mechanisms which eg avoids pulling new versions of dependencies which may contain malicious code (1 2 3). Github actions usually refer to other actions via version tags. This is fundamentally broken as git tags are mutable. Neither does the SHA pinnig really work because you have no guarantees that the dependency you are using is also using SHA pinning in its own dependencies! This means that using any external action opens a door to attacks. You have absolutely no guarantees that you are not pulling some newly introduced malicious code into your systems.

You are probably aware of the recent huge issue where every single version tag was changed to contain malware in the widely used tj-actions/changed-files. (ref1 / ref2) Neither does SHA pinning this action in your own dependencies work because it is most probably used already as a non pinned transient dependency (1)!

You really need to reconsider reopenning the issue: actions/runner#2195

Github really needs to step up with their security game on ensuring such supply chain attacks are no longer possible!

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[pronebird]

Please provide lock file for actions. Also consider introducing mechanism that would automatically reject running workflow that contains unknown/unpinned action

[jsoref]

Note that you actually can do full dependency constraints for uses::
https://docs.github.com/en/organizations/managing-organization-settings/disabling-or-limiting-github-actions-for-your-organization#allowing-select-actions-and-reusable-workflows-to-run

Apache has a specific list of allowed shas, their basic docs are https://infra.apache.org/github-actions-policy.html + https://cwiki.apache.org/confluence/display/BUILDS/GitHub+Actions+Security (I don't have the time to search for the thing, but they basically have a way to add specific sha entries to the org-wide allow list and automatically remove older versions).

[pronebird]

Pinning actions to hashes is a nightmare in terms of maintenance.

[jsoref]

That's what lock files are. A nightmare.

Note that GitHub's version isn't quite the same. It's an allow list of versions that applies all the way down the chain (until the software switches to running dynamic code).

That means that you can probably just add new versions for the deeper dependencies to your list, then intermediate dependencies, and finally the new versions of things you actually use. once you've done that, people are free to update components without writing a lock file for each repository. And there's no risk of them messing up the lock file or pulling in something too new or too old.

You still have the very real problem of an action turning out to be dangerous before you update your allow list, but, that's really a problem just about everywhere.

[pronebird]

That sounds too difficult. What I would consider:

• a manifest holding versions of each component along with auto generated hashes
• omit versions in workflows themselves

That's how dependencies work in many programming languages.

[jsoref]

And where do you want to put this lock file? one per repository? You'd still have to update each repository with your new lock files.

If you actually want, you can implement a version of this today...

on:
  push:
jobs:
  something:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v6
    - uses: your-org/enforce-action-versions@main
    - uses: some-org/some-action@v3
    - uses: some-other-org/some-other-action@v2

Where your-org/enforce-action-versions rummages through some rules and rewrites all of the items in the locally downloaded actions directory.

[pronebird]

And where do you want to put this lock file? one per repository? You'd still have to update each repository with your new lock files.

If you actually want, you can implement a version of this today...

on:

  push:

jobs:

  something:

    runs-on: ubuntu-latest

    steps:

    - uses: actions/checkout@v6

    - uses: your-org/enforce-action-versions@main

    - uses: some-org/some-action@v3

    - uses: some-other-org/some-other-action@v2

Where your-org/enforce-action-versions rummages through some rules and rewrites all of the items in the locally downloaded actions directory.

Same way it works in go, rust, node and other tech. The lock file is a part of repository where actions are being used.

Thanks for suggestion.