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Check Version Pinning GitHub Action

This GitHub Action scans your workflow files to ensure all GitHub Actions are securely pinned to a SHA hash, rather than a version tag (@v). Using SHA pinning aligns with best practices to protect against unintended changes in third-party actions.

Purpose

According to GitHub's security guidance, third-party actions should be pinned to a commit hash rather than a version tag for enhanced security. For instance, prefer this format:

uses: oxsecurity/megalinter/flavors/python@32c1b3827a334c80026c654f31ee1b4801ad8798

over:

uses: oxsecurity/megalinter/flavors/python@v1

This Action inspects workflows to detect and report any actions that are not SHA-pinned, helping to secure your CI/CD pipeline.

Features

  • Simple SHA Check: This Action scans workflows based on the string after the @ symbol to verify SHA pinning.

  • Targeted Organisations: No organisations are treated as implicitly trusted, ensuring that all third-party actions must be SHA-pinned without exceptions.

  • Customisable Scanning Modes: Run a full scan of your repository or focus on changes within a pull request.

Inputs

workflow_directory

Specifies the directory to scan for workflow files. Defaults to .github/workflows if not set.

scan_mode

Defines the scope of the scan:

  • full: Scans all workflows in the specified directory.
  • pr_changes: Scans only changes within a pull request (PR).

Outputs

Provides a list of any unpinned actions detected in the repository.

Example Usage

Here's a typical workflow setup that uses this Action to enforce SHA pinning on actions:

name: 🧪 Check Version Pinning

on:
  push:
    branches:
      - main
  pull_request:
  workflow_dispatch:

jobs:
  check-version-pinning:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          fetch-depth: 0  # Disable shallow clones for a more comprehensive scan

      - name: Check for unpinned Actions
        uses: ministryofjustice/github-actions/check-version-pinning@ccf9e3a4a828df1ec741f6c8e6ed9d0acaef3490 # v18.5.0
        with:
          workflow_directory: ".github/workflows" # Or wherever your workflows are stored
          scan_mode: "full"  # or "pr_changes" for PR-specific scans

Why This Action?

We initially considered using actionlint but found it too restrictive for our use case. This Action is lightweight and focuses solely on verifying SHA pinning for third-party actions, making it simpler and more tailored to specific security needs.

Notes

This Action will:

  • Flag any action with a version tag (e.g., @v1) rather than a SHA.

  • Not detect cases where third-party actions do not use semantic versioning or the v prefix in version tags.

  • Require all actions to be SHA-pinned, without any implicit trust for specific organisations like ministryofjustice or actions.

By adding this Action to your workflows, you can ensure a more secure CI/CD setup that prevents accidental usage of unpinned or untrusted actions.