They fail when the organisation relies on ad hoc judgement, incomplete protocol knowledge, or overloaded reviewers who cannot explain why a flagged event was or was not escalated. In that situation, detection may still occur, but the control breaks at the decision stage, where competence and consistency matter most.
Why informal anomaly review breaks the control
nerc cip-015 only works when the organisation can turn detection into a disciplined, explainable decision. If reviewers rely on intuition, partial protocol knowledge, or inconsistent thresholds, the control becomes a screening exercise rather than a control outcome, because the organisation cannot show that similar anomalies were treated consistently.
That failure usually shows up at the handoff between alerting and escalation. The event may be noticed, but if the reviewer cannot justify why it stayed open or moved forward, the control has not really been exercised in a repeatable way.
Where competence and consistency matter most
The weakness is not usually that anomalies are invisible. It is that the decision logic is undocumented, unevenly applied, or dependent on a few overextended people who know the environment well enough to recognise something “odd” but not well enough to classify it reliably under pressure.
Informal evaluation also creates drift over time. As staffing changes, event volume grows, and protocol knowledge becomes uneven, the same signal can be escalated one week and dismissed the next, which makes the control hard to defend during review or audit.
What practical failure looks like in operations
In practice, the organisation ends up with detection without determination. Alerts may accumulate, but the team cannot consistently explain the basis for escalation, the evidence required to suppress an alert, or the conditions that should trigger a second look.
That is why the control fails at the decision stage rather than the sensing stage. The operational gap is usually not lack of data, but lack of a standard for interpreting that data when the reviewer must make a call quickly and under workload pressure. For teams implementing the broader NERC CIP posture, the NERC CIP Guide is the natural reference point for how CIP-015 fits into the wider compliance and monitoring model.
Risk and Threat Considerations
When anomaly review is informal, the control can miss the difference between an unusual but benign event and an early indicator of compromise or misuse. The risk is inconsistent escalation, weak evidence for decisions, and a blind spot created by reviewer overload rather than by the absence of monitoring.
Failure mechanism: Ad hoc judgement replaces repeatable triage criteria, so reviewers cannot reliably explain why an event was or was not escalated, and the organisation cannot prove consistent control operation.
Impact: Suspicious activity may be normalised, incident response may start late, and audit evidence may show that detection existed without a defensible escalation decision.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-53 Rev 5 and NIST CSF 2.0 set the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | AU-6 — Audit Record Review, Analysis, and Reporting | Informal anomaly evaluation depends on consistent review and escalation of audit evidence. |
| SI-4 — System Monitoring | The question concerns how monitored anomalies are evaluated and acted on in operations. | |
| Recommendation — Define review criteria and escalation thresholds for anomalous events. Tune monitoring to flag events that require explainable analyst action. | ||
| NIST CSF 2.0 | DE.CM-01 — Anomalies and events are monitored to find cybersecurity events | CIP-015-style anomaly handling maps to monitored events needing consistent interpretation. |
| RS.CO-02 — Incidents are reported consistent with established criteria | The issue is the decision to escalate or not, which depends on clear reporting criteria. | |
| Recommendation — Establish repeatable triage rules for monitored anomalies. Use documented criteria to decide when anomalies must be escalated. | ||
| ISO/IEC 27001:2022 | A.8.16 — Monitoring activities | Formal monitoring needs defined evaluation so reviewers do not rely on ad hoc judgement. |
| Recommendation — Specify how monitoring findings are reviewed and escalated. | ||
Practitioner Guidance
What to verify: Check whether the team can produce a written decision rule for the most common anomaly classes, plus examples showing how similar events were handled the same way. If the only answer is “the reviewer knew it was fine,” the control is too informal to trust.
What to prioritise: Standardise escalation criteria before tuning alert volume further. Reducing noise helps, but it does not fix a process that depends on personal judgement the organisation cannot reproduce or explain.
Common mistake: Treating reviewer experience as a substitute for procedural clarity. Experience is valuable, but the control fails when the environment changes and the reasoning cannot be transferred to another analyst, shift, or audit cycle.
Practitioner takeaway: CIP-015 is only effective when anomaly handling is explainable, repeatable, and resilient to staff turnover and workload spikes; otherwise detection exists, but decision quality does not.
Related resources from NHI Mgmt Group
Deepen Your Knowledge
Free weekly newsletter
Subscribe to the NHI & AI Identity Journal
The latest on NHI and Agentic AI security – articles, research, breaches, news and events every week.
Bonus 33% off our NHI Course when you subscribe.
Reviewed and updated by the NHIMG editorial team on October 22, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org