OT Penetration Test Scope: Improving Security While Protecting Production
The success of an OT penetration test is not defined by the number of findings alone; it is defined by how safely the exercise is executed without production impact. Scope design must explicitly protect safety functions, interlocks, and always-on process lines. Testing should never start without a jointly approved window, access boundaries, and emergency stop procedure documented between the test team and plant operations.
Methodology should prioritize passive discovery, log review, and configuration assessment before any active technique. If active validation is required, target tolerance, load profile, and maintenance timing must be reviewed in advance. Legacy OT devices are especially sensitive to aggressive scanning, so controlled packet rates, safe command sets, and rollback strategy are mandatory. This keeps the assessment from becoming an operational disruption.
Stop criteria must be explicit and enforceable: unexpected CPU spikes, process alarms, communication latency anomalies, invalid device responses, or control instability should trigger immediate pause. These indicators should be visible to both operations and testing teams in a shared monitoring view, with one designated decision owner. Fragmented communication can quickly escalate a minor technical issue into a production event.
Reporting must rank findings not only by technical severity but also by operational consequence. Each issue should include a practical remediation path, accountable owner, target date, and verification method. When results are communicated clearly to security, engineering, and leadership together, penetration testing becomes a measurable improvement cycle rather than a one-time audit artifact.
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