Actions: Fix Critical Artifact poisoning False Positive

[AdnaneKhan]

The artifact poisoning CodeQL query creates a Critical false-positive under the following scenario:

• Download Artifact with path set to start with ${{ runner.temp }}
• Use of a PoisonableCommandStep

I believe this PR will fix it because it unless the path extraction functionality in CodeQL resolves/sanitizes the context values in some way.

Below is an example that reproduces the false positive:

name: Test False Positive
on:
  workflow_run:
    workflows:
      - Benchmark
    types:
      - completed

permissions:
  contents: read

jobs:
  benchmark:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Download From PR
        uses: actions/download-artifact@v4
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          run-id: ${{ github.event.workflow_run.id }}
          path: ${{ runner.temp }}/artifacts/
      - run: npm install

This is particularly a problem because the examples for a secure workflow specifically calls out this fix.

name: Secure Workflow

on:
  workflow_run:
    workflows: ["Prev"]
    types:
      - completed

jobs:
  Download:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - run: mkdir -p ${{ runner.temp }}/artifacts/
      - uses: dawidd6/action-download-artifact@v2
        with:
          name: pr_number
          path: ${{ runner.temp }}/artifacts/

      - name: Run command
        run: |
          sh cmd.sh

[Copilot]

Copilot wasn't able to review any files in this pull request.

Files not reviewed (1)

• actions/ql/lib/codeql/actions/security/ArtifactPoisoningQuery.qll: Language not supported

[JarLob]

Hi, I was pinged about it by Simon.

@AdnaneKhan you need to add a change note, see https://github.com/github/codeql/pull/19085/files#diff-a654ec6cec8af7e22ef1dc59ec11f5095d05128d97d67cdb2cbfe98e0fec6210 for an example.
Also a test is needed in actions/ql/test/query-tests/Security/CWE-829.

@tausbn @asgerf, can we have a review to have tests run? I wonder if it breaks anything. It looks fishy to me that the original tmp check was added in the first place as sanitizer as if it prevents code execution from the untrusted artifact if it was downloaded to tmp.

[JarLob]

See comments above.

[AdnaneKhan]

Hi, I was pinged about it by Simon.

@AdnaneKhan you need to add a change note, see https://github.com/github/codeql/pull/19085/files#diff-a654ec6cec8af7e22ef1dc59ec11f5095d05128d97d67cdb2cbfe98e0fec6210 for an example. Also a test is needed in actions/ql/test/query-tests/Security/CWE-829.

@tausbn @asgerf, can we have a review to have tests run? I wonder if it breaks anything. It looks fishy to me that the original tmp check was added in the first place as sanitizer as if it prevents code execution from the untrusted artifact if it was downloaded to tmp.

Thanks - I added a change note and a test workflow file but I'm not sure how to specify the test - is the ArtifactPoisoningCritical.expected file an assertion on the state of the codeql graph?