Real-time monitoring identifies an Industrial Control System (ICS) protocol write to a parameter/setpoint register where the written value falls outside the documented safe operating range, or where the write originates from a source not in the approved write-source list, correlated with subsequent historian tag drift. Documented precedent: FrostyGoop directly modified Modbus holding register values on ENCO heating controllers in Lviv, Ukraine, causing a two-day remediation outage. 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.
| Data Component | Name | Channel |
|---|---|---|
| Process History/Live Data (DC0107) | operationaldb:ProcessHistory | tag value deviates from rolling baseline mean by more than parameter drift threshold percent within time window following a flagged write |
| Network Traffic Content (DC0085) | NSM:Content | write function code (FC 6/16) to setpoint address range with value outside baseline value range, or from source not in approved write sources |
| Application Log Content (DC0038) | scada:applog | parameter write logged without corresponding operator_id in the Human-Machine Interface (HMI) audit trail |
| Field | Description |
|---|---|
| ApprovedWriteSources | IP allowlist of sources authorized to write to parameter/setpoint registers. |
| BaselineValueRange | Documented safe operating range for each monitored parameter. |
| ParameterDriftThreshold | Percentage deviation from rolling baseline considered significant drift. |
| SetpointAddressRange | Register/address ranges corresponding to parameter and setpoint values for the device type. |
| TimeWindow | Time window over which post-write drift is measured. |
Real-time monitoring identifies a Linux process invoking Industrial Control System (ICS) vendor write Application Programming Interfaces (APIs) or Open Platform Communications (OPC) Unified Architecture (UA) write calls to setpoint tags on field devices, from a User Identifier (UID) not associated with the authorized control application, with values exceeding the safe operating range. 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.
| Data Component | Name | Channel |
|---|---|---|
| Network Traffic Content (DC0085) | NSM:Content | decoded ICS protocol write/setpoint operation to a control/output address from a client identity or source not in the approved control-application baseline |
| Field | Description |
|---|---|
| ApprovedWriteSources | IP allowlist of sources authorized to write to parameter/setpoint registers. |
| BaselineValueRange | Documented safe operating range for each monitored parameter. |
| ParameterDriftThreshold | Percentage deviation from rolling baseline considered significant drift. |
| SetpointAddressRange | Register/address ranges corresponding to parameter and setpoint values for the device type. |
| TimeWindow | Time window over which post-write drift is measured. |
Real-time monitoring identifies a process on an Industrial Control System (ICS) Windows host writing setpoint values to Open Platform Communications (OPC) Data Access (DA)/Unified Architecture (UA) tags or historian writable tags without being the recognized Supervisory Control and Data Acquisition (SCADA) or Distributed Control System (DCS) control application, with values falling outside the normal operating range. 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.
| Data Component | Name | Channel |
|---|---|---|
| Application Log Content (DC0038) | opc:applog | write to setpoint tag from client not in approved Open Platform Communications (OPC) clients with value outside baseline value range |
| Field | Description |
|---|---|
| ApprovedWriteSources | IP allowlist of sources authorized to write to parameter/setpoint registers. |
| BaselineValueRange | Documented safe operating range for each monitored parameter. |
| ParameterDriftThreshold | Percentage deviation from rolling baseline considered significant drift. |
| SetpointAddressRange | Register/address ranges corresponding to parameter and setpoint values for the device type. |
| TimeWindow | Time window over which post-write drift is measured. |