Because they assume access can remain in place until the next review without creating meaningful risk. In modern environments, job changes, risk signals, contracts, and project assignments can invalidate access long before the review occurs. The review may confirm the problem, but it does not prevent the exposure window.
Why This Matters for Security Teams
Periodic access reviews are useful for confirming ownership and spotting obvious drift, but they are a weak primary control when access changes faster than the review cycle. That gap matters because modern environments are fluid: people change roles, projects end, contractors leave, and non-human identities continue operating long after the original justification has expired. By the time a quarterly or annual review is completed, the exposure window may already have been exploited.
This is especially true for secrets, service accounts, and machine credentials that are not tied to a human manager’s workflow. The control problem is not simply who approved access last time. It is whether access is still warranted right now. NHIMG’s Top 10 NHI Issues and the NIST Cybersecurity Framework 2.0 both point practitioners toward continuous governance rather than point-in-time reassurance. In practice, many security teams discover stale access only after a downstream incident has already validated it for an attacker.
How It Works in Practice
Periodic reviews fail as the main control because they are retrospective. They ask whether access looked reasonable at the last checkpoint, not whether it is safe under current conditions. For human identities, that can leave months of unnecessary access in place. For NHIs, the problem is sharper: tokens, API keys, certificates, and service credentials often run independently of employee lifecycle events, so a review may miss an active credential path entirely.
The stronger model is layered and runtime-driven. Current guidance from the OWASP Non-Human Identity Top 10 and NHIMG’s Ultimate Guide to NHIs emphasizes lifecycle control, continuous validation, and explicit ownership. In practice, that means:
- Assign every NHI to a business or system owner who can attest to necessity.
- Use short-lived credentials where possible, with automated expiry and revocation.
- Trigger review from events such as role changes, project closure, anomaly detection, or secret rotation failure.
- Pair access reviews with telemetry from PAM, IAM, secrets managers, and workload logs.
- Remove standing access by default and re-issue only when a current business need is proven.
Periodic review still has value as a detective and compliance activity, especially for audit evidence and entitlement cleanup. But as a primary governance control it is too slow for systems where access can be created, copied, or abused in minutes. The 2024 ESG report on NHIs notes that organisations experiencing a compromised NHI averaged 2.7 separate incidents in the past 12 months, which underscores how persistent the downside can be when stale access is not removed quickly. These controls tend to break down in high-change environments with many service accounts, federated apps, and decentralized ownership because no review cycle can keep pace with daily entitlement drift.
Common Variations and Edge Cases
Tighter access governance often increases operational overhead, requiring organisations to balance reduced exposure against approval latency and administrative burden. That tradeoff is real, especially where engineering teams need rapid access for deployments, incident response, or temporary integrations. Best practice is evolving toward risk-based review frequency instead of uniform calendar cycles, with the highest-risk NHIs reviewed continuously and lower-risk access sampled or attested on a longer schedule.
There is no universal standard for this yet, but several patterns are clear. Shared service accounts are the hardest to govern through periodic review because ownership is diffuse and business justification is often undocumented. Federated SaaS and cloud workloads are another weak spot, because a review can approve access that was already cached in a token or scope grant. For those cases, policy should focus on key challenges and risks across the full lifecycle, not just the next certification date. NIST guidance on security controls also supports treating access governance as an ongoing process rather than a periodic checkbox.
The practical takeaway is simple: periodic reviews should confirm that other controls are working, not substitute for them. If an entitlement can create meaningful exposure between review cycles, then the organisation has a control gap, not a review problem.
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 and CSA MAESTRO address the attack and risk surface, while NIST CSF 2.0, NIST SP 800-53 Rev 5 and NIST AI RMF set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-01 | Periodic reviews miss stale non-human access and ownership drift. |
| NIST CSF 2.0 | PR.AC-4 | Least-privilege access should be maintained as conditions change. |
| NIST SP 800-53 Rev 5 | AC-2 | Account management requires timely removal and review of access rights. |
| NIST AI RMF | Governance should assess ongoing risk, not just point-in-time approval. | |
| CSA MAESTRO | Agentic and machine workloads need runtime governance, not periodic checks. |
Continuously validate NHI ownership, necessity, and expiry instead of relying on calendar-based attestations.
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on August 11, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
