Detections

Real-time monitoring identifies iptables/nftables rules on Industrial Control System (ICS) Linux gateways that selectively drop ICS reporting message traffic based on content while allowing command traffic to pass. 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.

Real-time monitoring identifies a firmware write command targeting a specific Input/Output (I/O) module slot address within a controller chassis from a source not in the approved engineering workstation list, distinguishing module-level firmware modification from main-processor firmware updates by its slot-addressed targeting. 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.

Real-time monitoring identifies a user-invoked action on an Industrial Control System (ICS) workstation immediately followed by a process execution chain inconsistent with normal ICS operations -- the user-driven trigger plus the resulting anomalous execution chain together distinguish this from generic malware execution. OT operational-fidelity gate: Alert only when the account/device/session violates the approved identity + source host/jump path/zone policy and is corroborated by access to a protected OT asset, execution, configuration change, or another security-relevant follow-on event. Suppress approved shift activity, vendor support, break-glass use, commissioning, and documented remote-access windows.

Real-time monitoring identifies Industrial Control System (ICS) master-role command traffic originating from a source not in the approved control server inventory, directed at multiple field devices in a pattern consistent with control-server behavior. Documented in Maroochy Water Services (falsified PDS/station addresses to impersonate the master) and the 2017 Dallas Siren incident (rogue radio transmitter to 156 sirens). OT operational-fidelity gate: Alert only when the master/station identity or source is not authorized for the target device and command function, or when a normally authorized master violates its configured role/sequence and produces a corroborating device/process-state change. Suppress legitimate redundancy/failover, hot-standby promotion, commissioning, and approved engineering master activity.

Real-time monitoring identifies a trusted, signed Windows system binary executing with command-line arguments inconsistent with its documented administrative purpose -- specifically arguments indicating payload decoding, remote content execution, or script invocation -- on an Industrial Control System (ICS) host. 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.

Real-time monitoring identifies a Windows process generating Industrial Control System (ICS) command messages to field device tags representing physical outputs, from a process that is not the recognized Supervisory Control and Data Acquisition (SCADA) or Distributed Control System (DCS) control application, targeting safety-critical output tags. 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.

Real-time monitoring identifies malformed or out-of-spec ICS protocol exchanges targeting an embedded device from a source outside the approved communication baseline. 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.

Real-time monitoring identifies inbound connections to Industrial Control System (ICS) Windows application servers from internet-routed Internet Protocol (IP) addresses. OT operational-fidelity gate: Alert only when the asset's documented role does not permit the connection and the destination/proxy/service is outside the approved communications profile, with process/service identity used as corroboration where available. Suppress approved vendor support, update repositories, remote operations, failover paths, and documented temporary connectivity.

Real-time monitoring identifies a loss of communication with serially-connected field devices correlated with a configuration change event on the serial-to-Ethernet gateway. Documented in the 2015 Ukraine attack, where Sandworm used malicious firmware to render serial-to-Ethernet converters inoperable. 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.

Real-time monitoring identifies field device access using credentials matching hardcoded values extracted from Industrial Control System (ICS) vendor firmware or configuration files, from a source with no legitimate operational role. Documented in TriStation 1131 v4.9.0 and earlier, which contained undocumented power-user accounts with hardcoded credentials. OT operational-fidelity gate: Alert only when the account/device/session violates the approved identity + source host/jump path/zone policy and is corroborated by access to a protected OT asset, execution, configuration change, or another security-relevant follow-on event. Suppress approved shift activity, vendor support, break-glass use, commissioning, and documented remote-access windows.

Real-time monitoring identifies Domain Name System (DNS) queries from Industrial Control System (ICS) host Internet Protocol (IP) addresses to external resolvers for domains not associated with any approved ICS vendor, particularly domains exhibiting Domain Generation Algorithm (DGA)-like patterns. OT operational-fidelity gate: Alert only when the asset's documented role does not permit the connection and the destination/proxy/service is outside the approved communications profile, with process/service identity used as corroboration where available. Suppress approved vendor support, update repositories, remote operations, failover paths, and documented temporary connectivity.

Real-time monitoring identifies a process loading a packet capture driver or executing a known capture utility on an Industrial Control System (ICS) host's network interface, from a process or account not associated with documented network analysis responsibilities. OT operational-fidelity gate: Do not alert on novelty, scan/read volume, or enumeration alone. Alert when the source role is not authorized for discovery/polling and the target scope, address/tag range, protocol, or rate deviates from the established operational baseline. Suppress normal SCADA/HMI/historian polling, commissioning, asset inventory, backup, diagnostics, and approved engineering activity.

Real-time monitoring identifies an Industrial Control System (ICS) protocol restart/reset command directed at a field device from a source not in the approved engineering workstation list, particularly where multiple devices receive restart commands within a short window. Documented precedent: Industroyer exploited CVE-2015-5374 via a crafted 18-byte User Datagram Protocol (UDP) packet to port 50000 on Siemens SIPROTEC relays. 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.

Real-time monitoring identifies an Industrial Control System (ICS) protocol message sequence placing a field device into firmware-update mode from a source not in the approved engineering workstation list, correlated with the device's alarm telemetry going silent within a short grace period without acknowledgment. Documented precedent: Industroyer exploited CVE-2015-5374 by sending a crafted packet that initiated an incomplete firmware update sequence on Siemens Protection Technology (SIPROTEC) relays. 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.

Real-time monitoring identifies authentication to an external remote access gateway using credentials associated with Industrial Control System (ICS)-role accounts, from a source geolocation or Autonomous System Number (ASN) inconsistent with the account's established usage pattern, immediately followed by that session establishing connectivity into the ICS network zone. Documented in VPNFilter, which specifically targeted routers and network edge devices. OT operational-fidelity gate: Alert only when the account/device/session violates the approved identity + source host/jump path/zone policy and is corroborated by access to a protected OT asset, execution, configuration change, or another security-relevant follow-on event. Suppress approved shift activity, vendor support, break-glass use, commissioning, and documented remote-access windows.

Real-time monitoring identifies a remote service connection between two Industrial Control System (ICS) network hosts that does not match the documented, approved communication matrix, where the destination host subsequently exhibits process execution or file access inconsistent with normal automated/scheduled inter-host communication. OT operational-fidelity gate: Alert only when the account/device/session violates the approved identity + source host/jump path/zone policy and is corroborated by access to a protected OT asset, execution, configuration change, or another security-relevant follow-on event. Suppress approved shift activity, vendor support, break-glass use, commissioning, and documented remote-access windows.

Much of this activity may have a very high occurrence and associated false positive rate, as well as potentially taking place outside the visibility of the target organization, making detection difficult for defenders.

Detection efforts may be focused on related stages of the adversary lifecycle, such as during Initial Access.

Much of this activity may have a very high occurrence and associated false positive rate, as well as potentially taking place outside the visibility of the target organization, making detection difficult for defenders.

Detection efforts may be focused on related stages of the adversary lifecycle, such as during Initial Access.

Much of this activity may have a very high occurrence and associated false positive rate, as well as potentially taking place outside the visibility of the target organization, making detection difficult for defenders.

Detection efforts may be focused on related stages of the adversary lifecycle, such as during Initial Access.

Much of this activity will take place outside the visibility of the target organization, making detection of this behavior difficult. Detection efforts may be focused on behaviors relating to the potential use of exploits for vulnerabilities (i.e. Exploit Public-Facing Application, Exploitation for Client Execution, Exploitation for Privilege Escalation, Exploitation for Stealth, Exploitation for Credential Access, Exploitation of Remote Services, and Application or System Exploitation).

Much of this activity may have a very high occurrence and associated false positive rate, as well as potentially taking place outside the visibility of the target organization, making detection difficult for defenders.

Detection efforts may be focused on related stages of the adversary lifecycle, such as during Initial Access.

Monitor for suspicious network traffic that could be indicative of adversary reconnaissance, such as rapid successions of requests indicative of web crawling and/or large quantities of requests originating from a single source (especially if the source is known to be associated with an adversary). Analyzing web metadata may also reveal artifacts that can be attributed to potentially malicious activity, such as referer or user-agent string HTTP/S fields.

Much of this activity may have a very high occurrence and associated false positive rate, as well as potentially taking place outside the visibility of the target organization, making detection difficult for defenders.

Detection efforts may be focused on related stages of the adversary lifecycle, such as during Initial Access.

Much of this activity may have a very high occurrence and associated false positive rate, as well as potentially taking place outside the visibility of the target organization, making detection difficult for defenders.

Detection efforts may be focused on related stages of the adversary lifecycle, such as during Initial Access.

Much of this activity may have a very high occurrence and associated false positive rate, as well as potentially taking place outside the visibility of the target organization, making detection difficult for defenders.

Detection efforts may be focused on related stages of the adversary lifecycle, such as during Initial Access.