github: prevent script injections via PR branch names #1083
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Prior this commit, ${{ github.event.workflow_run.head_branch }} got
expanded in the bash script. A malicious actor could inject
an arbitrary shell script. Since this action has access to a token
with write rights the malicious actor can easily steal this token.
This commit moves the expansion into an env block where such an
injection cannot happen. This is the preferred way according to the
github docs:
https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-an-intermediate-environment-variable
supakeen
approved these changes
Dec 2, 2024
True, but I'll admit I never pay too much attention to the BRANCH NAME before approving a run. |
thozza
approved these changes
Dec 3, 2024
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Prior this commit, ${{ github.event.workflow_run.head_branch }} got expanded in the bash script. A malicious actor could inject an arbitrary shell script. Since this action has access to a token with write rights the malicious actor can easily steal this token.
This commit moves the expansion into an env block where such an injection cannot happen. This is the preferred way according to the github docs:
https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-an-intermediate-environment-variable
Note that we don't allow external contributors to run CI without our manual approval, so this could not actually be abused.