Coordinated Disclosure Timeline
- 2020-12-22: Report sent to vendor.
- 2021-01-18: Issue partially fixed.
- 2021-01-25: Vendor acknowledges report receipt and informs about the fix.
- 2021-01-25: Information about the not fixed parts sent.
- 2021-01-25: Issue resolved.
Summary
The GitHub workflows pull-request.yml in multiple branches of tophat/networkjs, tophat/commit-utils, tophat/commit-watch, tophat/sanity-runner and commit-watch.yml in tophat/commit-watch are vulnerable to unauthorized modification of the base repository or secrets exfiltration from a Pull Request.
Product
tophat/networkjs GitHub repository
tophat/commit-utils GitHub repository
tophat/commit-watch GitHub repository
tophat/sanity-runner GitHub repository
Tested Version
The latest versions to the date.
Details
Issue: Untrusted code is explicitly checked out and run on a Pull Request from a fork
Workflows triggered on pull_request_target have read/write tokens for the base repository and the access to secrets. By explicitly checking out and running the build script from a fork the untrusted code is running in an environment that is able to push to the base repository and to access secrets. More details can be found in the article Keeping your GitHub Actions and workflows secure: Preventing pwn requests.
on:
- pull_request_target
...
- uses: actions/checkout@v2
with:
ref: ${{ github.event.pull_request.head.sha }}
- uses: ./.github/actions/detect-node
...
- name: Install dependencies
run: yarn install --immutable
- name: Linting
run: yarn lint:ci
- name: Tests
run: yarn test:ci
...
Impact
The vulnerability allows for unauthorized modification of the base repository and secrets exfiltration.
Credit
This issue was discovered and reported by GHSL team member @JarLob (Jaroslav Lobačevski).
Contact
You can contact the GHSL team at securitylab@github.com, please include a reference to GHSL-2020-371 in any communication regarding this issue.