Detection of Block Ethernet

Technique Detected:  Ethernet | T1695.002

ID: DET0911
Domains: ICS
Analytics: AN2054, AN2165, AN2204, AN2214
Version: 1.0
Created: 22 April 2026
Last Modified: 13 October 2026

Analytics

AN2054

Real-time monitoring identifies a Windows network-adapter disable or administrative interface-down event on an ICS gateway or protocol-converter host outside the approved network-maintenance window. 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
Application Log Content (DC0038) WinEventLog:System network adapter disabled on Industrial Control Systems (ICS) gateway host by process not in authorized network admins
Mutable Elements
Field Description
ApprovedNMSCIDR IP ranges authorized for switch configuration changes.
ChangeControlWindow Scheduled maintenance periods during which interface configuration changes are authorized.

AN2165

Real-time monitoring identifies ip link set down commands on Industrial Control System (ICS) Linux gateway hosts by a User Identifier (UID) not in the authorized net admin UIDs, affecting the device subnet interface. 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
Process Creation (DC0032) auditd:SYSCALL Linux Audit SYSCALL/EXECVE/SOCKADDR records (configured audit rule): syscall=execve; ip link command disables an interface on an ICS gateway outside the authorized network-administration baseline
Mutable Elements
Field Description
ApprovedNMSCIDR IP ranges authorized for switch configuration changes.
ChangeControlWindow Scheduled maintenance periods during which interface configuration changes are authorized.

AN2204

Real-time monitoring identifies a switch interface transitioning to administratively-down state on a port connected to an Industrial Control System (ICS) field device, from a configuration change source not in the approved network administration list. 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
Application Log Content (DC0038) networkdevice:syslog interface shutdown command on Industrial Control Systems (ICS) device port from source not in approved Network Management System (NMS) Classless Inter-Domain Routing (CIDR) subnet outside change control window
Mutable Elements
Field Description
ApprovedNMSCIDR IP ranges authorized for switch configuration changes.
ChangeControlWindow Scheduled maintenance periods during which interface configuration changes are authorized.

AN2214

Real-time monitoring identifies device_ip offline alarm coinciding with switch port admin-down syslog for that port, distinguishing deliberate Ethernet blocking from physical disconnection. 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 offline alarm coinciding with switch port admin-down syslog for that port
Mutable Elements
Field Description
ApprovedNMSCIDR IP ranges authorized for switch configuration changes.
ChangeControlWindow Scheduled maintenance periods during which interface configuration changes are authorized.