Detection of Hooking

Real-time monitoring identifies a process setting LD_PRELOAD before launching an Industrial Control System (ICS) service binary, or writing to /etc/ld.so.preload, where the injected library path is not part of the vendor's package manifest. OT operational-fidelity gate: Alert only when execution violates an approved signer/hash/path/parent/process or tool allowlist, or originates from an unauthorized user/tool, and is tied to an OT asset or follow-on OT-relevant action. Suppress vendor-signed software, approved engineering utilities, diagnostics, patching, backup, and documented maintenance.

Detect embedded hooking by correlating an independently acquired firmware/module integrity measurement that differs from the approved vendor/baseline image with protocol-response behavior that also departs from the device's known deterministic behavior. A protocol-response anomaly by itself does not prove a hook because firmware versions, device state, communications faults, and vendor-specific behavior can produce response differences. Treat network anomalies as corroboration and require independent integrity evidence or vendor/device attestation before escalating the condition as firmware-level hooking. Monitoring mode: periodic or event-triggered integrity verification plus near-real-time protocol monitoring where a capable OT protocol decoder is deployed.

Real-time monitoring identifies ICS protocol responses whose timing or payload structure deviates from the established device-specific per-function baseline in a pattern consistent with an intercepting relay or hook. OT operational-fidelity gate: Alert only when execution violates an approved signer/hash/path/parent/process or tool allowlist, or originates from an unauthorized user/tool, and is tied to an OT asset or follow-on OT-relevant action. Suppress vendor-signed software, approved engineering utilities, diagnostics, patching, backup, and documented maintenance.