Why do access reviews often miss SoD violations?

Why Access Reviews Miss SoD Violations

Access reviews are designed to confirm what was true at a point in time, but segregation of duties failures are often created by motion, not snapshots. A user can gain a conflicting entitlement after certification through role drift, delegated admin rights, emergency access, or a change in upstream group membership. That is why a clean review can still be followed by a toxic access path days later.

The problem is even sharper for non-human identities, where service accounts, API keys, and automation roles are frequently over-privileged and under-observed. NHIs are often invisible in standard governance workflows, and only 5.7% of organisations say they have full visibility into their service accounts, according to the Ultimate Guide to NHIs. That gap makes SoD exceptions easy to miss until an incident forces reconstruction after the fact. Current guidance from the OWASP Non-Human Identity Top 10 treats unmanaged credential sprawl and weak lifecycle controls as core drivers of NHI risk, not edge cases.

In practice, many security teams discover the SoD failure only after an audit finding, a production outage, or a privileged workflow has already crossed trust boundaries.

How It Works in Practice

Effective SoD control needs continuous entitlement monitoring, not just periodic certification. The practical answer is to combine access review evidence with event-driven detection: watch for role changes, new group inheritance, delegated administration grants, standing privilege accumulation, and new secrets issuance. For NHIs, that means tracking the workload identity, the secret lifecycle, and the actual runtime permissions separately rather than assuming one account equals one purpose. The 52 NHI Breaches Analysis shows how often identity failures become breach paths when governance does not follow the credential lifecycle.

A stronger operating model usually includes:

• JIT access for privileged actions, so conflicting privileges exist only for the task window.
• Runtime policy checks for each request, rather than relying on a quarterly approval.
• Separate review of human users, service accounts, and automation identities, because their risk patterns differ.
• Rotation and expiry rules for secrets, tokens, and certificates so access cannot silently persist beyond intent.

This is where identity governance meets workload security. The NHI Lifecycle Management Guide is useful because SoD is rarely just an entitlement problem; it is also a creation, rotation, delegation, and offboarding problem. For implementation detail, the OWASP Non-Human Identity Top 10 aligns well with secrets hygiene, least privilege, and identity lifecycle controls. These controls tend to break down in environments with shared admin tooling, legacy batch jobs, or broad RBAC groups because ownership and effective access become difficult to trace in real time.

Common Variations and Edge Cases

Tighter SoD control often increases operational overhead, requiring organisations to balance separation against release speed, emergency response, and automation reliability. That tradeoff is real, especially where production support depends on break-glass access or where pipelines need temporary elevated permissions to complete deployments.

Best practice is evolving here, and there is no universal standard for every environment. In mature programmes, the answer is usually not to forbid overlap entirely, but to constrain it with context, expiry, and evidence. That means documenting which conflicting privileges are acceptable only under JIT approval, which workflows need compensating controls, and which identity types must never hold standing cross-functional access. For agentic workloads, the issue gets harder because autonomous systems may chain tools and escalate actions faster than a periodic review can observe. The Ultimate Guide to NHIs — Key Challenges and Risks is particularly relevant because it ties excessive privilege to broad attack surface, which is exactly why static certification misses the real exposure.

Where organisations often struggle is in hybrid estates with SaaS admin roles, inherited cloud permissions, and service accounts shared across pipelines. In those cases, SoD review quality depends less on the review form and more on whether entitlement changes, secret creation, and delegated access are instrumented as continuous signals.

Related resources from NHI Mgmt Group

• How should security teams run access reviews for non-human identities?
• When do NHI access reviews create more value than a one-time cleanup?
• When should organisations replace access reviews with continuous validation for NHIs?
• What do auditors look for in access review and SoD testing?