Why do manual Segregation of Duties reviews create fraud risk in modern enterprises?

Manual SoD reviews create risk because access data is too large and too distributed to track reliably by spreadsheet. Modern enterprises may have thousands of access records, multiple business applications, and changing roles across IT and business teams. That complexity makes omissions, delayed reviews, and inconsistent decisions more likely, which can leave toxic access combinations in place long enough for fraud to occur.

Why manual SoD reviews fail at enterprise scale

Manual segregation of duties reviews usually start with a simple idea, but the operating reality is not simple at all. Access data is fragmented across ERP, SaaS, cloud, and legacy systems, then filtered through spreadsheets and human judgment. That makes it easy to miss cross-system conflicts, stale exceptions, and role changes that should have triggered a new review.

Once the review process depends on exports, reconciliations, and subjective interpretation, the control becomes highly sensitive to timing. A review may be “completed” while entitlements have already changed, which means the assurance is about a past state rather than current access. In practice, that gap is where toxic combinations survive long enough to matter.

Manual review also struggles with volume and ambiguity. The same access bundle can look acceptable in one business context and risky in another, especially when the reviewer lacks a consistent rule set for entitlements, inherited roles, temporary access, and compensating controls.

Why manual judgment creates a fraud window

The fraud risk is not just that someone makes a bad decision. The deeper problem is that manual reviews often create a lag between risk creation and risk detection. During that lag, a person with conflicting permissions can initiate, approve, and conceal a transaction path before anyone notices the combination.

This is why segregation of duties is a control design issue, not just an audit exercise. If the review process cannot keep pace with role churn, exception handling, and distributed application ownership, the organisation is effectively relying on delayed human memory to stop an access pattern that should have been prevented or flagged automatically.

That lag also weakens accountability. When a review is spread across multiple teams, nobody owns the full entitlement picture end to end, so unresolved conflicts can be normalized as “known exceptions” rather than treated as control failures requiring action.

What modern enterprises must control instead of spreadsheet drift

A reliable SoD programme needs an authoritative entitlement view, consistent conflict rules, and a defensible exception workflow. The control should detect conflicts across applications and roles, not just within a single system, and it should distinguish approved mitigations from unmanaged exceptions.

For enterprises with service accounts, bots, or automated workflows, the review model also has to account for non-human access that can execute business actions. Those accounts may not be the main fraud actor, but they can amplify a conflicting permission path if they are granted broad operational access without review discipline.

Automation does not remove the need for judgement, but it does move judgement to the right place. The useful human task is to approve exceptions, investigate unusual combinations, and decide whether a conflict is genuinely mitigated, rather than manually reconstructing access from spreadsheets every cycle.

Risk and Threat Considerations

Manual SoD reviews create exposure because they are easy to outgrow. As the number of systems, roles, and exception cases increases, missed conflicts, stale approvals, and inconsistent mitigation decisions become more likely, which increases the chance that a toxic access path remains active long enough for abuse.

Failure mechanism: The control fails when reviewers cannot reliably see all relevant entitlements, cannot apply the same rule consistently across systems, or cannot update decisions fast enough after role changes or temporary access events.

Impact: Fraudulent initiation, approval, reconciliation, or override paths can remain available, and later review may only confirm that the conflict existed after the loss window has already opened.

Standards & Framework Alignment

This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.

OWASP Non-Human Identity Top 10 addresses the attack surface, NIST SP 800-53 Rev 5 and CIS Controls v8 set the technical controls, and ISO/IEC 27001:2022 defines the regulatory obligations.

Framework	Control / Reference	Relevance
NIST SP 800-53 Rev 5	AC-5 — Separation of Duties	Directly addresses SoD conflicts and conflicting privileges.
	AC-6 — Least Privilege	Reduces the toxic access combinations that manual reviews often miss.
	AU-6 — Audit Review, Analysis, and Reporting	Supports detection of conflicting activity after access is granted.
Recommendation — Apply AC-5 to separate incompatible duties and review compensating controls for exceptions. Limit permissions to the minimum needed to reduce SoD conflict exposure. Use AU-6 to analyse activity for signs that conflicting access is being abused.
CIS Controls v8	CIS-6 — Access Control Management	Covers managing and reviewing access rights, role assignment, and privilege creep.
Recommendation — Implement CIS-6 to centralise access review and remove conflicting privileges promptly.
ISO/IEC 27001:2022	A.5.15 — Access control	Requires controlled access rights and governance over who can do what.
Recommendation — Enforce A.5.15 to govern access approvals, reviews, and exceptions consistently.
OWASP Non-Human Identity Top 10	NHI-05 — Overprivileged NHI	Manual review gaps also matter for automated and non-human accounts with excessive access.
	NHI-01 — Improper Offboarding	Stale access after role change or exit is a common SoD and fraud exposure.
Recommendation — Review non-human access for overprivilege and remove conflicting permissions. Revoke obsolete access quickly when duties change or accounts are no longer needed.

Practitioner Guidance

What to prioritise: Treat SoD as a live entitlement control, not a periodic audit packet. Focus first on the transactions and role combinations that can move value, post entries, approve payments, or override controls, then map where those permissions live across systems.

What to verify: Before trusting a review, verify that the entitlement source is complete, the conflict rules are versioned, and exceptions have an expiry, owner, and compensating control that is actually tested.

Practitioner takeaway: The core control objective is not to make manual review “more thorough”, but to remove the dependence on memory, spreadsheets, and delayed reconciliation for conflicts that can directly enable fraud.