ISO/IEC 27001:2022 A.5.3 — Segregation of duties

What this control requires

Conflicting duties and conflicting areas of responsibility shall be segregated.

In plain English

Conflicting duties and conflicting areas of responsibility shall be segregated. In practice, this means you can prove you policy responsibility-level controls on a defined cadence.

Why it matters

ISO 27001 certification depends on showing each Annex A control is either implemented or explicitly justified for exclusion in the Statement of Applicability (SoA). Certification bodies sample controls during surveillance audits, and a missing SoA entry — or implementation that doesn't match the SoA wording — is a finding.

This control is rated high. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation.

What an auditor looks for

An ISO 27001 lead auditor looks for: (1) an SoA entry covering the control with justification, (2) a documented procedure or policy implementing it, (3) records that prove the procedure runs (logs, tickets, training records) and (4) management-review evidence that effectiveness is monitored.

Within Organizational controls, the assessor will trace your implementation back to the catalogue reference (Annex A A.5.3) and look for objective evidence on the latest two assessment cycles.

How to implement

Policy Management

Docs. Keep each policy in version-controlled Markdown alongside the code that implements it; ship a signed PDF snapshot at each annual review and link the SHA into the SoA.

Operational checklist

• Policy. Document the trigger, the owner and the cadence.
• Segregation. Document the trigger, the owner and the cadence.
• Management. Document the trigger, the owner and the cadence.
• Responsibility. Document the trigger, the owner and the cadence.
• Scope: responsibility, management.

Evidence to collect

• Policy Document. A signed and version-controlled policy / standard / procedure document.
• Infra Scan. Continuous infrastructure-posture telemetry — AWS Config, Azure Policy compliance, GCP Organisation Policy, Wiz / Prisma findings.

Signed policy or standard documents the safeguard. Focus: Segregation of duties.

Common pitfalls

• Policies that no engineer has read; the version in Confluence drifts from the version that's actually being enforced.

How it maps to other frameworks

Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit.

• SOC 2 (2017 TSC) CC2.3 — External Communication on Internal Control Matters
• ISO/IEC 42001:2023 A.2.2 — Policies for the responsible development or use of AI systems
• HIPAA (45 CFR Part 164) 164.308(a)(5)(i) — Security Awareness and Training
• NIST SP 800-171 Rev. 3 3.13.15 — Session Authenticity
• BSI C5:2020 SP-01 — Documentation, communication and provision of policies and instructions

Related controls in ISO/IEC 27001:2022

• Annex A A.5.5 — Contact with authorities
• Annex A A.5.13 — Labelling of information
• Annex A A.5.30 — ICT readiness for business continuity
• Annex A A.5.37 — Documented operating procedures
• Annex A A.5.1 — Policies for information security
• Annex A A.5.4 — Management responsibilities

References

• ISO/IEC JTC 1/SC 27 — ISO/IEC 27001:2022
• Catalogue identifier: Annex A A.5.3

Topics: governance risknetwork segmentationpolicy management