ICS Alert: Command Blocked

Rule ID

PH_RULE_ICS_Block_Command_Message

Default Status

Enabled

Description

An ICS monitoring system has detected an event containing Mitre ICS Technique ID T0803 - Block Command Message. Adversaries may block a command message from reaching its intended target to prevent command execution. In OT networks, command messages are sent to provide instructions to control system devices. A blocked command message can inhibit response functions from correcting a disruption or unsafe condition.

Severity

MITRE ATT&CK® Tactics

Inhibit Response Function

MITRE ATT&CK® Techniques

Impacts

Network

Data Source

Dragos Platform via Syslog and Nozomi SCADA Guardian/CMC via NOZOMI_API

Detection

Correlation

Remediation Guidance

Investigate the source, and determine if the event was legitimate.

Time Window

If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.

300 seconds

Trigger Conditions

If the following defined pattern/s occur within a 300 second time window.

mitre_ics_event

SubPattern Definitions

SubPattern Name: mitre_ics_event

This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.

SubPattern Query

This is the query logic that matches incoming events

(eventType CONTAIN "FortiDeceptor-" OR eventType CONTAIN "Dragos-" OR eventType CONTAIN "Nozomi-")  AND  attackTechniqueId REGEXP "^(T\d+,)*T0803(,T\d+)*$"

Group by Attributes

This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID

srcIpAddr,destIpAddr,eventType

Aggregate Constraint

This is most typically a numerical constraint that defines when the rule should trigger an incident

COUNT(*) >= 1

Incident Attribute Mapping

This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.

The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern

 compEventType=mitre_ics_event.eventType,
srcIpAddr=mitre_ics_event.srcIpAddr,
destIpAddr=mitre_ics_event.destIpAddr,
incidentCount=mitre_ics_event.COUNT(*)

FortiSIEM Rules