Coordinated Disclosure Timeline

• 2020-12-22: Report sent to maintainers.
• 2020-12-22: Maintainers acknowledged.
• 2021-01-26: Asked maintainers for status update.
• 2021-01-26: Maintainers asked for more details about the vulnerability.
• 2021-01-26/27: Provided additional explanation.
• 2021-02-23: Asked maintainers for status update.
• 2021-02-23: Maintainers responded that they work on rewriting the code, but “in the mean time have to run this risk”.
• 2021-02-23: Notified maintainers, that disclosure deadline is in a month.
• 2021-02-23: Maintainers responded stating they do not consent to public advisory publication.
• 2021-02-23: Security Lab replied with a reference to our disclosure policy, and by stating that since there is no redistributable software we will not issue any GHSA or request a CVE.
• 2021-03-22: Disclosure deadline reached.
• 2021-04-01: Asked maintainers for status update and notified that more than 90 days have passed.
• 2021-04-01: A fix is applied to remove vulnerable workflows.
• 2021-04-01: Publication as per our policy.

Summary

The process-disclosure.yml GitHub workflow is vulnerable to unauthorized modification of the base repository or secrets exfiltration from a Pull Request.

Product

418sec/huntr GitHub repository

Tested Version

The latest changeset be289b1 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
...
      - id: checkout
        uses: actions/checkout@v2
        with:
          fetch-depth: 0
          ref: refs/pull/${{ github.event.number }}/merge
...
      - id: dependency-install
        name: Install npm dependencies
        run: npm ci
      - id: generate-diff
        name: Generate the diff
        env:
          PR_NUMBER: ${{ github.event.pull_request.number }}
          GITHUB_TOKEN: ${{ secrets.HUNTR_HELPER_TOKEN }}
        run: node ./generate-diff.js
...

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-2020-372 in any communication regarding this issue.