Detection of Change Operating Mode

Technique Detected:  Change Operating Mode | T0858

ID: DET0755
Domains: ICS
Analytics: AN1887
Version: 1.0
Created: 21 October 2025
Last Modified: 12 May 2026

Analytics

AN1887

Real-time monitoring identifies an Industrial Control System (ICS) protocol mode-change command targeting a field device from a source not in the approved engineering workstation list, where the transition is not immediately followed by a corresponding operator acknowledgment. Documented in Triton (the Tricon controller had to be placed in PROGRAM mode before the attack could inject its payload). OT operational-fidelity gate: Alert only when the action is not attributable to an authorized operator/engineering source for the specific target and function, and it is either outside an approved change/maintenance window or lacks matching change-control context; where telemetry permits, require corroborating device, configuration, or process-state effect. Suppress activity that fully matches approved maintenance, commissioning, failover, recovery, or tested control procedures.

Log Sources
Data Component Name Channel
Device Alarm (DC0108) operationaldb:AlarmEvent device mode-change alarm generated without corresponding operator_id entry within mode change ack window
Network Traffic Content (DC0085) NSM:Content mode-change service from source not in engineering workstation list outside change control window
Application Log Content (DC0038) engineeringworkstation:ApplicationLog mode-change session logged without corresponding change ticket reference
Mutable Elements
Field Description
ChangeControlWindow Scheduled maintenance periods during which mode changes are authorized.
EngineeringWorkstationList IP allowlist of workstations authorized to issue mode-change commands.
ModeChangeAckWindow Time window within which a legitimate operator acknowledgment is expected following a mode-change event.