In this ultimate how to implement guide to ISO 27001 Annex A 8.4 Access to Source Code, you will learn directly from an ISO 27001 Lead Auditor:
- The requirement of the control
- The required implementation steps
- The minimum requirement
I am Stuart Barker, the ISO 27001 Lead Auditor and author of the Ultimate ISO 27001 Toolkit.
Using over 30 years of industry experience across hundreds of audits, I’m giving you the exact templates, walkthroughs, and practical examples you need to achieve ISO 27001 certification.
Table of contents
- ISO 27001 Access to Source Code Implementation Checklist
- 1. Enforce Strict RBAC on Version Control Systems
- 2. Implement Branch Protection Rules
- 3. Deploy Pre-Commit Secret Scanning
- 4. Restrict Access to CI/CD Configuration Files
- 5. Mandate GPG Signing for Commits
- 6. Secure Local Source Code Storage
- 7. Segregate Read vs. Write Permissions
- 8. Implement IP Allow-Listing for Repository Access
- 9. Establish a Private Dependency Proxy
- 10. Conduct Quarterly Access Revocation Reviews
- ISO 27001 Annex A 8.4 SaaS / GRC Platform Implementation Failure Checklist
Implementing ISO 27001 Annex A 8.4 is the technical enforcement of Access to Source Code protocols to protect intellectual property and software integrity. This control mandates strict Role-Based Access Control (RBAC), branch protection rules, and cryptographic code signing to prevent unauthorised modifications and mitigate software supply chain attacks.
ISO 27001 Access to Source Code Implementation Checklist
Use this implementation checklist to achieve compliance with ISO 27001 Annex A 8.4 by physically restricting and technically verifying who can read, write, and modify your organisation’s intellectual property. Effective control relies on rigorous Git configuration and identity management, not on uploading a policy document to a compliance portal.
1. Enforce Strict RBAC on Version Control Systems
Control Requirement: Access to program source code must be restricted to authorised personnel only. Required Implementation Step: Log into your repository host (GitHub, GitLab, Bitbucket). Audit the “Teams” or “Groups” configuration. Remove any “All Employees” groups from having default read access to private repositories. Explicitly assign developers only to the specific repositories required for their current project sprint.
Minimum Requirement: The principle of ‘Least Privilege’ applied to repo visibility; Sales and HR must have zero access.
2. Implement Branch Protection Rules
Control Requirement: Changes to source code must be controlled and authorised. Required Implementation Step: Configure the `main` or `master` branch settings to “Block direct pushes”. Enable “Require pull request reviews before merging” and set the minimum number of reviewers to at least one senior developer.
Minimum Requirement: No single developer can push code to production without a documented peer review.
3. Deploy Pre-Commit Secret Scanning
Control Requirement: Source code must not contain sensitive information like credentials or keys. Required Implementation Step: Install local pre-commit hooks using tools like `trufflehog` or `git-secrets` on all developer workstations. Configure the CI/CD pipeline to fail the build immediately if high-entropy strings (potential API keys) are detected in the commit history.
Minimum Requirement: Automated prevention of hard-coded passwords entering the version control history.
