GHSL-2024-159: Poisoned Pipeline Execution (PPE) in an Actions workflow of Element+

Coordinated Disclosure Timeline

• 2024-07-10: Opened an issue asking for a security point of contact.
• 2024-08-02: Reported through GitHub’s Private Vulnerability Reporting (PVR).
• 2024-08-02: Fix is shared for review.
• 2024-08-05: Fix is merged.

Summary

Element+ is vulnerable to Poisoned Pipeline Execution (PPE) which may allow an attacker to gain write acces to the repository and the CROWDIN_TOKEN token.

Project

Element+

Tested Version

Latest commit at the time of reporting

Details

Poisoned Pipeline Execution in publish-docs-deploy.yml (GHSL-2024-159)

The publish-docs-deploy.yml workflow gets triggered when the Publish to NPM registry workflow finished. The workflow checks out the HEAD SHA of the event triggering the workflow run:

- name: Checkout
  uses: actions/checkout@v4
  with:
    ref: ${{ github.event.workflow_run.head_sha }}
    persist-credentials: false

After checking out the code, the workflow runs a number of steps using pnpm such as:

- name: Init Crowdin token
  run: pnpm run docs:crowdin-credentials
  env:
    CROWDIN_TOKEN: ${{secrets.CROWDIN_TOKEN}}

An attacker would be able to submit a Pull Request with two changes:

1. Modify .github/workflows/publish-npm.yml to: ```yml name: Publish to NPM registry on: pull_request: jobs: test: runs-on: ubuntu-latest steps:
   • run: echo “Should run on release” ```
2. Modify package.json line for “docs:crowdin-credentials” script to include arbitrary commands:

   ...
     "scripts": {
    ...
    "docs:crowdin-credentials": "echo PWNED",
    ...
     },
   ...
   

This Pull Request will trigger the execution of vulnerable workflow and will run arbitrary commands in the context of a write-all privileged workflow.

Impact

This issue may lead to gain full write access to the elements+ repository and steal secrets.

Resources

• CodeQL for JavaScript - Expression injection in Actions
• Keeping your GitHub Actions and workflows secure Part 2: Untrusted input
• Keeping your GitHub Actions and workflows secure Part 1: Preventing pwn requests

Credit

This issue was discovered and reported by GHSL team member @pwntester (Alvaro Muñoz).

Contact

You can contact the GHSL team at securitylab@github.com, please include a reference to GHSL-2024-159 in any communication regarding this issue.