ISO 27001:2022 Annex A 5.21 – Managing Information Security in the ICT Supply Chain Explained

ICT supply chains introduce risk long before systems go live.

Annex A 5.21 exists to ensure organisations manage information security risks associated with ICT products and services throughout the supply chain, rather than assuming those risks are addressed by suppliers by default.

This control recognises that hardware, software, cloud services, and managed platforms are often built, delivered, and supported by multiple parties — not all of whom are visible without deliberate oversight.

ISO 27001

Quick Guide: Annex A 5.21 at a Glance

Annex A 5.21 of ISO 27001:2022 focuses on managing information security risks in the ICT supply chain.

At a practical level, this means:

  • Understanding how ICT products and services are sourced and delivered
  • Identifying security risks introduced by ICT suppliers and subcontractors
  • Defining security expectations specific to ICT supply
  • Gaining assurance that supplied components are legitimate and secure
  • Managing ICT supply chain risk throughout the lifecycle

The control does not require exhaustive inspection of supplier environments or deep technical audits of every component. It expects risk-based governance and proportionate assurance.

In-Depth Guide to Annex A 5.21

What Is Annex A 5.21 and Why Does It Matter?

ICT supply chains are complex.

They often involve:

  • Multiple layers of suppliers and subcontractors
  • Reused or third-party components
  • Cloud and shared infrastructure
  • Limited visibility beyond the primary supplier

This creates risks such as:

  • Introduction of vulnerable or malicious components
  • Dependency on unsupported or legacy elements
  • Inability to trace the origin of critical components
  • Reduced ability to influence security practices downstream

Annex A 5.21 ensures organisations actively manage these risks, rather than discovering them after deployment or during incidents.

How to Implement Annex A 5.21 Effectively

A pragmatic approach to Annex A 5.21 typically includes the following elements.

1. Identify ICT Supply Chain Scope

Organisations should understand which suppliers provide:

  • ICT products
  • ICT services
  • Components critical to availability, integrity, or confidentiality

Focus should be placed on suppliers whose failure or compromise would have material impact.

2. Assess ICT-Specific Supply Chain Risks

ICT supply chain risk often depends on:

  • Type of service or component provided
  • Level of access to systems or data
  • Criticality of the service to operations
  • Ability to influence or control supplier behaviour

Risk assessment should drive the level of assurance required.

3. Define ICT-Specific Security Expectations

Security requirements for ICT suppliers often go beyond generic supplier controls.

These may include expectations relating to:

  • Secure development and delivery practices
  • Component integrity and authenticity
  • Change management and notification
  • Protection against tampering or unauthorised modification

Expectations should be clear, relevant, and achievable.

4. Seek Appropriate Assurance of Supplied Products and Services

Organisations commonly seek assurance through:

  • Supplier-provided documentation
  • Independent certifications or attestations
  • Technical validation or testing
  • Confirmation of component provenance

Assurance should be proportionate to risk and practical to maintain.

5. Manage Subcontracting and Downstream Risk

Where ICT suppliers rely on subcontractors, organisations should consider:

  • Visibility of critical subcontracted components or services
  • Flow-down of security requirements
  • Accountability for downstream failures

Unmanaged subcontracting is a frequent source of hidden exposure.

6. Address Unsupported or Legacy Components

ICT supply chains often include components that are:

  • Unsupported
  • End-of-life
  • Difficult to replace

Where this occurs, organisations should deliberately manage risk through:

  • Compensating controls
  • Planned replacement strategies
  • Increased monitoring or restriction

Ignoring legacy risk does not reduce it.

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.

Common Challenges and How to Overcome Them

  • Assuming large or well-known suppliers are low risk
  • Assess risk based on service impact, not brand recognition
  • Lack of visibility beyond the primary supplier
  • Focus on critical components and dependencies
  • Overly generic supplier security requirements
  • Tailor controls to ICT-specific risks
  • Accepting components without assurance
  • Seek reasonable evidence of integrity and legitimacy

ICT supply chain risk increases when complexity is ignored.

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 5.21 is about maintaining confidence in what you introduce into your environment.

When ICT supply chain security is managed effectively:

  • Hidden dependencies are reduced
  • Component integrity is better understood
  • Risk is addressed before deployment
  • Operational resilience improves

Organisations do not need full control over their ICT supply chains. They do need sufficient visibility and assurance to avoid operating blindly.

That is the outcome Annex A 5.21 is designed to achieve.

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