Protecting GitHub Actions

GitHub Actions provides powerful automation capabilities for your repositories. To ensure the security and integrity of your workflows, it’s important to implement measures that protect your GitHub Actions and associated resources. This guide outlines best practices and answers common questions regarding GitHub Actions protection.

Table of contents

Prohibiting Changes to GitHub Actions

To prevent unauthorized modifications to your GitHub Actions, follow these steps:

1. Enforce Branch Protection Rules:

   • Configure branch protection rules in your repository settings, specifically for branches containing your GitHub Actions workflow files.
   • Enable the option to require pull request reviews before merging changes to these protected branches.
   • This ensures that any modifications to your GitHub Actions workflow files go through a thorough review process before being merged.

2. Implement Code Review:

   • Require code reviews for pull requests that modify the GitHub Actions workflow files.
   • Use the repository’s code review features to ensure that changes are reviewed and approved by authorized individuals.
   • This helps identify and address any potential security vulnerabilities or misconfigurations in your workflows.

Scoping Secrets to Specific Workflow/Job/Step

To control the usage of secrets within specific workflows, jobs, or steps, consider the following recommendations:

1. Define Repository Secrets:

   • Define secrets at the repository level using the GitHub repository settings.
   • Access these secrets within your workflows by referencing their names.

2. Conditional Secret Usage:

   • Leverage conditional expressions in your workflow files to conditionally use secrets based on specific criteria.
   • Use the if expressions to define conditions such as branch names, event types, or other contextual information.
   • Restricting secret usage to the necessary parts of your workflows minimizes exposure.

Example:

steps:
  - name: Deploy to Production
    run: deploy.sh
    env:
      PROD_SECRET: ${{ secrets.PRODUCTION_SECRET }}
    if: github.ref == 'refs/heads/main'

In this example, the PROD_SECRET secret is only exposed when the workflow is triggered on the main branch.

Calling Scripts from Third-Party Repositories

While it’s possible to call scripts from third-party repositories in GitHub Actions, caution must be exercised to ensure security:

1. Use Trusted Sources:

   • Only use scripts from trusted sources or maintain your own forked versions of external repositories.
   • Conduct thorough reviews of the scripts and validate their content before incorporating them into your workflows.
   • Evaluate the reputation, community support, and maintenance status of the third-party repository.

2. Consider Security Risks:

   • Executing scripts from external sources introduces security risks, including the potential for malicious code.
   • Always inspect the code and consider running it in a controlled environment before using it in production workflows.
   • Regularly review and update any third-party scripts used in your workflows to incorporate security patches and improvements.

By following these best practices, you can enhance the security of your GitHub Actions and mitigate potential risks. Remember to regularly review and update your workflows to incorporate new security measures and stay informed about the latest best practices.

For additional information, consult the official GitHub Actions documentation and security guidelines.