ISO 27001 A.5.3: segregation of duties, explained for startups
What A.5.3 asks of a small company, and what an auditor samples.
Split up sensitive tasks so no single person can misuse a process end to end. This makes fraud and honest mistakes far harder to slip through unnoticed.
Why it exists: to stop one person from making and approving the same sensitive change alone.
A.5.3 Segregation of duties
No one person can carry out and approve the same sensitive change alone. What proves it: a short list of the duties that must be split, who holds each side, and proof the split is enforced.
A certification auditor samples a segregation of duties matrix and a sample of changes showing a different approver. A file that usually does the job: a one-page duties matrix, or code host settings showing that a different person must approve each change.
How to put it in place
Each step leaves a record, and the record is what the auditor samples rather than the step itself. Inside Polara, the control card for A.5.3 walks you through it in this order.
- List the sensitive actions: production deploys, access grants, payments, key changes.
- For each, name who does it and who approves it, and make sure they are different people.
- Turn on the setting that enforces it where a tool can (for example required reviewers on the main branch).
No question in the readiness assessment covers A.5.3 directly, so the control card is its whole evidence path.
Policies, connectors and the SOC 2 overlap
In the ISO 27001 policy pack, the Information Security Policy covers A.5.3. An auditor reads the policy for the rule, then samples the records to see the rule was followed.
The same evidence counts toward SOC 2. The Trust Services criteria that cover this ground: CC5.1, choosing controls and CC8.1, change management.
Organizational controls
A.5.3 is one of the 37 organizational controls in Annex A. How the company runs security: policies, roles, suppliers, incidents, continuity and legal duties. Most of these are written decisions and the records that show you follow them.
Nearby controls in the same theme:
- A.5.1, security policies
- A.5.2, security roles
- A.5.4, what managers must enforce
- A.5.5, contact with authorities
- A.5.6, security communities
Before it: A.5.2, security roles. After it: A.5.4, what managers must enforce. Every control, by theme, is on the Annex A controls page.
Questions
What does ISO 27001 A.5.3 require?
What evidence does an auditor want for A.5.3?
Get ready for ISO 27001 certification.
The readiness assessment is free, with no payment and no card. ISO 27001 is part of Constellation, at $10,800 a year: everything in Orbit plus the management system, the policies, the evidence and the management review for ISO 27001, and your SOC 2 Type 2 audit is included in every contract year. You contract the certification body directly.
The internal audit is priced separately: Polara arranges it with an independent internal auditor from our partner network who works in the platform, and quotes it for your company.
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