ISO 27001:2022 Annex A 8.4 Access to source code

In this guide, I will show you exactly how to implement ISO 27001 Annex A 8.4 and ensure you pass your audit. You will get a complete walkthrough of the control, practical implementation examples, and access to the ISO 27001 templates and toolkit that make compliance easy.

I am Stuart Barker, an ISO 27001 Lead Auditor with over 30 years of experience conducting hundreds of audits. I will cut through the jargon to show you exactly what changed in the 2022 update and provide you with plain-English advice to get you certified.

Key Takeaways: ISO 27001 Annex A 8.4 Access to Source Code

ISO 27001 Annex A 8.4 requires organizations to strictly manage read and write access to their source code, development tools, and software libraries. The goal is to protect your Intellectual Property (IP) and, more importantly, to prevent the unauthorized introduction of “rogue” code or backdoors that could lead to a catastrophic security breach.

Core requirements for compliance include:

• Least Privilege Access: Only developers actively working on a specific project should have access to its repository. Access should be revoked immediately when a developer leaves the company or changes teams.
• Controlled Write Access: “No one pushes directly to Main.” You must use a branching strategy where code changes can only be merged into production via a Pull Request (PR) and after an authorized review.
• Integrity Protection: You should use digital signatures or commit signing (e.g., GPG keys in Git) to verify that the person who supposedly wrote the code is actually the person who submitted it.
• Library Management: Access to software libraries and third-party components must be managed to ensure developers aren’t using unapproved or vulnerable open-source code.
• Logging & Monitoring: All read and write activities in your code repository (e.g., GitHub, GitLab, Bitbucket) must be logged and periodically reviewed for suspicious patterns.

Audit Focus: Auditors will look for “The Rogue Developer” defense:

1. Repository Proof: “Show me the settings for your core repository. Do you have ‘Branch Protection’ enabled?”
2. Access Review: “Show me the user list for your GitLab account. How many people have ‘Admin’ vs. ‘Developer’ rights?”
3. The “Leaving” Test: They may cross-reference your HR “Leavers List” with your GitHub user list to see if former employees still have access to your code.

Repository Security Checklist (Audit Prep):

Setting	Recommendation	Why?
Pull Requests	Mandatory	Prevents direct, unvetted pushes to production code.
Code Review	Min. 1 Approver	Ensures a second pair of eyes catches security flaws.
Branch Protection	Enabled	Locks the production branch from unauthorized deletion or changes.
GPG Signing	Recommended	Provides cryptographically verifiable proof of authorship.
MFA	Mandatory	Stops repository compromise if a developer’s password is stolen.

What is ISO 27001 Annex A 8.4?

ISO 27001 Annex A 8.4 is about access to source code which means you must protect your source code and have a process to manage read and write access to it.

ISO 27001 Annex A 8.4 Access To Source Code is an ISO 27001 control that wants you to make sure you have controls in place around access to code.

ISO 27001 Annex A 8.4 Purpose

The purpose of ISO 27001 Annex A 8.4 Access To Source Code is to prevent the introduction of unauthorised functionality, avoid unintentional or malicious changes and to maintain the confidentiality of valuable intellectual property.

ISO 27001 Annex A 8.4 Definition

The ISO 27001 standard defines Annex A 8.4 as:

Read and write access to source code, development tools and software libraries should be appropriately managed.

ISO 27001:2022 Annex A 8.4 Access To Source Code

ISO 27001 Annex A 8.4 Free Training Video

In the video ISO 27001 Access To Source Code Explained – ISO27001:2022 Annex A 8.4 I show you how to implement it and how to pass the audit.

ISO 27001 Annex A 8.4 Explainer Video

In this beginner’s guide to ISO 27001 Annex A 8.4 Access To Source, ISO 27001 Lead Auditor Stuart Barker and his team talk you through what it is, how to implement in and how to pass the audit. Free ISO 27001 training.

ISO 27001 Annex A 8.4 Podcast

In this episode: Lead Auditor Stuart Barker and team do a deep dive into the ISO 27001 Annex A 8.4 Access To Source Code. The podcast explores what it is, why it is important and the path to compliance.

How to implement ISO 27001 Annex A 8.4

Applicability

If you have source code then you want to protect access to it. If you do not then this is not in scope for you, you can update your statement of applicability to put it out of scope, add it to the risk register and accept the risk.

You are going to manage access to your source code, program code, libraries and associated software. The requirement is to stop unauthorised modification that can lead to an information security incident.

The Three Pillars of Implementation

The effective implementation of Annex A 8.4 is a continuous process that is built on three foundational pillars that ensure that your controls are robust, documented and resilient.

• Risk Based Foundation: assess assets and threats to implement proportionate controls
• Documented Process and Governance: formalise policies and procedures for access management
• Continuous Assurance and Monitoring: establish mechanisms for logging, monitoring and control effectiveness

Pillar 1: Risk Based Approach

• Risk Assessment: Conduct a risk assessment to identify all repositories of source code, program code, libraries and associated software.
• Threat Modelling: Understand the specific threats to each code asset.
• Proportionate controls: Implement proportionate controls based on risk.

Pillar 2: Documented Process and Governance

If you do have source code then you already know what to do as there is nothing revolutionary in this particular control. The control is looking for documentation and maturity of process of what you already do. The required documentation includes:

• ISO 27001 Access Control Policy: governs access including access to source code.
• ISO 27001 Secure Development Policy: details the requirements for source code access in the development lifecycle.
• Process and Procedural records of evidence: records of changes, updates, reviews, monitoring and logging.

Pillar 3: Assurance

You will ensure that there is ongoing assessment of the effectiveness of the controls. Activities include:

• Logging and monitoring: implement logging to create audit trails of read/write access and codebase changes
• Integrity Verification: employ digital signatures where required to provide assurance of code integrity
• Third Party Assurance: consider escrow services for high value code bases

Repository Security Checklist

Setting	Recommendation	Why?
Require Pull Request	YES	No one pushes directly to Main.
Require Approvals	Min. 1 Reviewer	Prevents “rogue” code changes.
Dismiss Stale Approvals	YES	If code changes, re-approval is needed.
Code Owners	Enabled	Only Senior Devs can approve sensitive files.

ISO 27001 Access Control Policy Template

The ISO 27001 Access Control Policy template is pre written and ready to go. It is one of the required ISO 27001 policies that sets out the organisations approach to access control.

ISO 27001 Secure Development Policy Template

The ultimate ISO 27001 Secure Development Policy Template including the ISO 27001 requirements for access to source code.

How to pass an ISO 27001 Annex A 8.4 audit

Top 3 ISO 27001 Annex A 8.4 mistakes and how to avoid them

The top 3 mistakes people make for ISO 27001 Annex A 8.4 are

1. Allowing everyone to access code

Depending on the size of teams, complexity and mix of internal and external resource the requirements for access restrictions on code can often get over looked. Be sure to understand and document the requirements, put in place processes and lock the access down based on organisation need and business risk.

2. Your code is on laptops

This common mistake actually relates to copies of your code being all over the place. It can be hard to manage code and developers and teams to maintain a single source of truth in a controlled way that protects your intellectual property and the integrity of the code base. Some people use check in and check out solutions but be aware of rogue copies of your code out in the real world and the risk it poses to you, usually in terms of that code being taken and used some where else for commercial gain without your approval or knowledge.

3. Your document and version control is wrong

Keeping your document version control up to date, making sure that version numbers match where used, having a review evidenced in the last 12 months, having documents that have no comments in are all good practices.

Fast Track Compliance with the ISO 27001 Toolkit

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Own Your ISMS, Don’t Rent It

Do it Yourself ISO 27001 with the Ultimate ISO 27001 Toolkit

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For ISO 27001 Annex A 8.4 (Access to source code), the requirement is to appropriately manage read and write access to source code, development tools, and software libraries. This is about protecting your most valuable intellectual property and preventing the introduction of unauthorized functionality.

Many organizations believe they need an expensive SaaS platform to “manage” their code repositories. However, your source code is already managed in tools like GitHub, GitLab, or Bitbucket. A compliance SaaS platform is not a repository manager; it is simply an expensive place to host your policies. The High Table ISO 27001 Toolkit is the logical, time-saving solution because it provides the governance framework you need to manage your actual code repositories effectively.

Here is why the Toolkit is the smarter choice for complying with Annex A 8.4:

1. Ownership: You Own Your Source Code Policy Forever

SaaS platforms act as a middleman for your compliance evidence. If you define your repository security rules and store your access reviews inside their proprietary system, you are essentially renting your own security standards.

• The Toolkit Advantage: You receive the Access Control Policy and Secure Development Policy in fully editable Word/Excel formats. These files are yours forever. You own the standards that define your repository settings (like branch protection and PR requirements), ensuring you are audit-ready without being held to a “subscription ransom.”

2. Simplicity: Governance for the Tools You Already Use

Annex A 8.4 is about the management of code access. You don’t need a complex new software interface to manage what your repository manager (like GitHub or GitLab) already does natively.

• The Toolkit Advantage: Your development team already knows how to manage repo permissions. What they need is the governance layer to prove to an auditor that these permissions are reviewed and follow the principle of least privilege. The Toolkit provides pre-written templates and checklists (like the Repository Security Checklist) that formalize your existing technical work into an auditor-ready framework, without forcing your team to learn a new software platform.

3. Cost: A One-Off Fee vs. Per-Developer Subscriptions

Many compliance SaaS platforms charge more as your engineering team grows or the number of “repositories” increases. For a control that applies to every piece of code your organization writes, these monthly costs can scale aggressively.

• The Toolkit Advantage: You pay a single, one-off fee for the entire toolkit. Whether you have 5 developers or 500, the cost of your Source Code Governance Documentation remains the same. You save your budget for the actual development tools your business needs, rather than an expensive compliance dashboard.

4. Freedom: No Vendor Lock-In for Your Repo Stack

SaaS compliance tools often only integrate with a limited number of “standard” repository managers. If you use a custom setup, on-prem repo, or switch providers, the SaaS tool can become a barrier to technical flexibility.

• The Toolkit Advantage: The High Table Toolkit is 100% technology-agnostic. You can edit the Access Procedures to match any technical environment. You maintain total freedom to evolve your development infrastructure without being constrained by the technical limitations of a rented SaaS platform.

Summary: For Annex A 8.4, an auditor wants to see that you have a policy for code access and proof that you follow it. The High Table ISO 27001 Toolkit provides the governance framework to satisfy this requirement immediately. It is the most direct, cost-effective way to achieve compliance using permanent documentation that you own and control.

Related ISO 27001 Controls

ISO 27001 Annex A 8.28 Secure Coding

ISO 27001 Annex A 8.25 Secure Development Life Cycle

ISO 27001 Annex A 8.29 Security Testing in Development and Acceptance

ISO 27001 Annex A 8.17 Clock Synchronisation

Further Reading

How To Create an ISO 27001 Threat Intelligence Process and Report

ISO 27001 Controls and Attribute Values

Control type	Information security properties	Cybersecurity concepts	Operational capabilities	Security domains
Preventive	Confidentiality	Protect	Identity and access management	Protection
	Integrity		Application Security
	Availability		Secure Configuration