ISO 27001:2022 Annex A 8.4 – Access to Source Code Explained

Source code is not just technical material.
It is intellectual property, operational logic, and security control all in one.

Annex A 8.4 exists to ensure organisations strictly control access to source code and associated development tools, preventing unauthorised disclosure, modification, or misuse.

This control is about protecting the blueprint of your systems, not just the systems themselves.

ISO 27001

Quick Guide: Annex A 8.4 at a Glance

Annex A 8.4 of ISO 27001:2022 focuses on controlling access to source code.

At a practical level, this means:

  • Restricting access to source code based on business need
  • Protecting source code from unauthorised change or disclosure
  • Managing read and write permissions deliberately
  • Recording and monitoring changes to source code
  • Applying structured change management to code access

The control does not prevent development activity. It expects organisations to separate creation, access, and approval deliberately.

In-Depth Guide to Annex A 8.4

What Is Annex A 8.4 and Why Does It Matter?

Source code often contains:

  • Business logic and proprietary processes
  • Credentials, keys, or configuration details
  • Security controls and enforcement logic
  • Integration details for other systems

If access to source code is uncontrolled:

  • Intellectual property may be exposed
  • Vulnerabilities may be introduced deliberately or accidentally
  • Malicious changes may go undetected
  • Recovery and investigation become difficult

Annex A 8.4 ensures organisations treat source code as a high-value information asset, not just a development by-product.

This control replaces ISO 27001:2013 Annex A 9.4.5 and introduces stronger emphasis on tooling, auditability, and structured access control.

How to Implement Annex A 8.4 Effectively

A pragmatic approach to Annex A 8.4 typically includes the following elements.

1. Define What Constitutes Source Code

Organisations should clearly define what is considered source code, which may include:

  • Application and system source code
  • Scripts and automation logic
  • Configuration-as-code
  • Build and deployment scripts
  • Specifications and design artefacts

Clear scope prevents accidental exclusion of critical material.

2. Restrict Access Based on Business Need

Access to source code should be:

  • Granted only to authorised individuals
  • Aligned to defined roles and responsibilities
  • Limited to what is required (read vs write)

Not everyone involved in IT requires direct access to source code.

3. Separate Read and Write Permissions

Annex A 8.4 explicitly supports differentiated access.

Organisations should consider:

  • Read-only access for review or support roles
  • Write access limited to authorised developers
  • Additional approval for sensitive repositories

Write access carries significantly higher risk than read access.

4. Use Source Code Management Systems

Access to source code should be controlled centrally.

This typically involves:

  • Source code repositories
  • Role-based access control
  • Centralised authentication
  • Consistent permission management

Ad-hoc storage of code undermines control and traceability.

5. Control Access Through Development Tools

ISO 27001:2022 places emphasis on indirect access.

Organisations may:

  • Provide access through development environments
  • Restrict direct access to raw repositories
  • Use tools that enforce permission and workflow controls

Tooling can enforce discipline where policy alone cannot.

6. Apply Change Management to Source Code

Access to source code should align with formal change control.

This includes:

  • Authorisation before changes are made
  • Review and approval of modifications
  • Testing and validation prior to deployment

Annex A 8.4 aligns closely with change management controls (see Annex A 8.32).

7. Maintain Audit Trails for Source Code Activity

Organisations should maintain records of:

  • Access to source code
  • Changes made
  • Who made changes and when

Audit trails support:

  • Incident investigation
  • Accountability
  • Compliance and assurance

Untracked change is unmanaged change.

8. Protect Source Code at Rest and in Transit

Source code repositories should be protected against:

  • Unauthorised access
  • Loss or corruption
  • Interception during transfer

This may include:

  • Secure storage
  • Encryption
  • Controlled backup and recovery

Protection should match the value of the code.

9. Use Integrity Controls for Published Code

Where code is released or shared externally, organisations may consider:

  • Integrity checking
  • Verification mechanisms
  • Controls that detect unauthorised modification

This protects both the organisation and downstream users.

In-Depth Guide to Annex A 5.1

What is Annex A 5.1 and Why Does It Matter?

  • What the organisation values
  • How security decisions are approached
  • Where accountability sits
  • Aligns security with business objectives
  • Supports proportionate, risk-based decisions
  • Provides a reference point during incidents and disputes
  • Creates consistency without bureaucracy

How to Implement Annex A 5.1 Effectively

1. Define a Comprehensive Information Security Policy
  • Scope: What the policy applies to (systems, data, people).
  • Objectives: Why security is important for the business.
  • Roles & Responsibilities: Who is accountable for security.
  • Key Principles: Risk management, access control, and data protection.
2. Secure Senior Management Approval
  • Review and approve policies.
  • Ensure resources are allocated for implementation.
  • Lead by example in enforcing security policies.
3. Communicate and Train Employees
  • Include security policies in onboarding and ongoing training.
  • Ensure policies are easily accessible to all employees.
  • Encourage acknowledgment and acceptance of security responsibilities.
4. Regular Review & Continuous Improvement
  • Set a schedule for periodic policy reviews (at least annually).
  • Update policies based on business changes, new threats, or regulatory updates.
  • Conduct audits to ensure compliance and effectiveness.
5. Integrate Policies into the ISMS
  • Use it to develop more detailed security procedures.
  • Ensure policies align with other Annex A controls and broader risk management practices.
Key Differences: ISO 27001:2013 vs ISO 27001:2022
AspectISO 27001:2013ISO 27001:2022
Control StructureTwo separate controls: 5.1.1 & 5.1.2Merged into one control (5.1)
Implementation GuidanceLess prescriptiveMore detailed guidance for policy creation and alignment
Awareness & TrainingNot explicitly mentionedExplicitly requires policies to be part of training programmes
Attributes TableNot includedew attributes table for mapping policies to industry terms
Common Challenges & How to Overcome Them
  • Challenge: Employees don’t follow security policies.
  • Solution: Make policies practical and relevant to daily work. Use real-world examples in training.
  • Challenge: Policies are outdated or too generic.
  • Solution: Schedule annual reviews and update policies based on real threats and business changes.
  • Challenge: Policies are written in technical jargon.
  • Solution: Use plain language that all employees can understand.
  • Challenge: Lack of leadership buy-in.
  • Solution: Show how weak security affects business objectives—costs of breaches, loss of client trust, and legal penalties.
Final Recommendations
  • Make security policies living documents—review, refine, and update regularly.
  • Use policy training and awareness to create a security-conscious workforce.
  • Ensure policies are accessible, relevant, and easy to understand.
  • Keep policies aligned with business strategy and regulatory requirements.
  • Engage leadership in driving security culture from the top down.

Practical Considerations

Annex A 8.4 does not require:

  • Eliminating collaboration
  • Preventing developers from doing their job
  • Complex tooling by default

It does require organisations to:

  • Protect intellectual property deliberately
  • Prevent unauthorised change
  • Be able to demonstrate control over code access

Source code incidents are often catastrophic, not incremental.

Common Challenges and How to Overcome Them

  • Shared repositories with broad access
  • Apply role-based read/write permissions
  • Direct access without audit trail
  • Use managed source code systems
  • Developers with unrestricted write access
  • Separate duties and enforce approval workflows
  • Ignoring scripts and configuration code
  • Treat all code consistently

Most source code compromise is preventable.

In-Depth Guide to Annex A 5.1

What is Annex A 5.1 and Why Does It Matter?

  • What the organisation values
  • How security decisions are approached
  • Where accountability sits
  • Aligns security with business objectives
  • Supports proportionate, risk-based decisions
  • Provides a reference point during incidents and disputes
  • Creates consistency without bureaucracy

How to Implement Annex A 5.1 Effectively

1. Define a Comprehensive Information Security Policy
  • Scope: What the policy applies to (systems, data, people).
  • Objectives: Why security is important for the business.
  • Roles & Responsibilities: Who is accountable for security.
  • Key Principles: Risk management, access control, and data protection.
2. Secure Senior Management Approval
  • Review and approve policies.
  • Ensure resources are allocated for implementation.
  • Lead by example in enforcing security policies.
3. Communicate and Train Employees
  • Include security policies in onboarding and ongoing training.
  • Ensure policies are easily accessible to all employees.
  • Encourage acknowledgment and acceptance of security responsibilities.
4. Regular Review & Continuous Improvement
  • Set a schedule for periodic policy reviews (at least annually).
  • Update policies based on business changes, new threats, or regulatory updates.
  • Conduct audits to ensure compliance and effectiveness.
5. Integrate Policies into the ISMS
  • Use it to develop more detailed security procedures.
  • Ensure policies align with other Annex A controls and broader risk management practices.
Key Differences: ISO 27001:2013 vs ISO 27001:2022
AspectISO 27001:2013ISO 27001:2022
Control StructureTwo separate controls: 5.1.1 & 5.1.2Merged into one control (5.1)
Implementation GuidanceLess prescriptiveMore detailed guidance for policy creation and alignment
Awareness & TrainingNot explicitly mentionedExplicitly requires policies to be part of training programmes
Attributes TableNot includedew attributes table for mapping policies to industry terms
Common Challenges & How to Overcome Them
  • Challenge: Employees don’t follow security policies.
  • Solution: Make policies practical and relevant to daily work. Use real-world examples in training.
  • Challenge: Policies are outdated or too generic.
  • Solution: Schedule annual reviews and update policies based on real threats and business changes.
  • Challenge: Policies are written in technical jargon.
  • Solution: Use plain language that all employees can understand.
  • Challenge: Lack of leadership buy-in.
  • Solution: Show how weak security affects business objectives—costs of breaches, loss of client trust, and legal penalties.
Final Recommendations
  • Make security policies living documents—review, refine, and update regularly.
  • Use policy training and awareness to create a security-conscious workforce.
  • Ensure policies are accessible, relevant, and easy to understand.
  • Keep policies aligned with business strategy and regulatory requirements.
  • Engage leadership in driving security culture from the top down.

Final Recommendations

Annex A 8.4 is about protecting the organisation’s intellectual and operational core.

When access to source code is managed effectively:

  • Intellectual property is protected
  • Unauthorised changes are prevented or detected
  • Accountability and traceability improve
  • Security weaknesses are less likely to be introduced

Applications run the business.
Source code defines how they behave.

Annex A 8.4 ensures that behaviour is controlled, intentional, and defensible.

In-Depth Guide to Annex A 5.1

What is Annex A 5.1 and Why Does It Matter?

  • What the organisation values
  • How security decisions are approached
  • Where accountability sits
  • Aligns security with business objectives
  • Supports proportionate, risk-based decisions
  • Provides a reference point during incidents and disputes
  • Creates consistency without bureaucracy

How to Implement Annex A 5.1 Effectively

1. Define a Comprehensive Information Security Policy
  • Scope: What the policy applies to (systems, data, people).
  • Objectives: Why security is important for the business.
  • Roles & Responsibilities: Who is accountable for security.
  • Key Principles: Risk management, access control, and data protection.
2. Secure Senior Management Approval
  • Review and approve policies.
  • Ensure resources are allocated for implementation.
  • Lead by example in enforcing security policies.
3. Communicate and Train Employees
  • Include security policies in onboarding and ongoing training.
  • Ensure policies are easily accessible to all employees.
  • Encourage acknowledgment and acceptance of security responsibilities.
4. Regular Review & Continuous Improvement
  • Set a schedule for periodic policy reviews (at least annually).
  • Update policies based on business changes, new threats, or regulatory updates.
  • Conduct audits to ensure compliance and effectiveness.
5. Integrate Policies into the ISMS
  • Use it to develop more detailed security procedures.
  • Ensure policies align with other Annex A controls and broader risk management practices.
Key Differences: ISO 27001:2013 vs ISO 27001:2022
AspectISO 27001:2013ISO 27001:2022
Control StructureTwo separate controls: 5.1.1 & 5.1.2Merged into one control (5.1)
Implementation GuidanceLess prescriptiveMore detailed guidance for policy creation and alignment
Awareness & TrainingNot explicitly mentionedExplicitly requires policies to be part of training programmes
Attributes TableNot includedew attributes table for mapping policies to industry terms
Common Challenges & How to Overcome Them
  • Challenge: Employees don’t follow security policies.
  • Solution: Make policies practical and relevant to daily work. Use real-world examples in training.
  • Challenge: Policies are outdated or too generic.
  • Solution: Schedule annual reviews and update policies based on real threats and business changes.
  • Challenge: Policies are written in technical jargon.
  • Solution: Use plain language that all employees can understand.
  • Challenge: Lack of leadership buy-in.
  • Solution: Show how weak security affects business objectives—costs of breaches, loss of client trust, and legal penalties.
Final Recommendations
  • Make security policies living documents—review, refine, and update regularly.
  • Use policy training and awareness to create a security-conscious workforce.
  • Ensure policies are accessible, relevant, and easy to understand.
  • Keep policies aligned with business strategy and regulatory requirements.
  • Engage leadership in driving security culture from the top down.

The Annex Control Table

ISO 27001:2022 Organisational Controls
ISO 27001:2022 Technological Controls