FortiSIEM Rules

User deleted from Administrator Group

Rule ID


Default Status



Detects users deleted from administrator group







Impact consists of techniques that adversaries use to disrupt availability or compromise integrity by manipulating business and operational processes. Techniques used for impact can include destroying or tampering with data. In some cases, business processes can look fine, but may have been altered to benefit the adversaries’ goals. These techniques might be used by adversaries to follow through on their end goal or to provide cover for a confidentiality breach.

MITRE ATT&CK® Techniques


Account Access Removal

Adversaries may interrupt availability of system and network resources by inhibiting access to accounts utilized by legitimate users. Accounts may be deleted, locked, or manipulated (ex: changed credentials) to remove access to accounts.



Data Source

Windows Security Log via OMI or FortiSIEM Agent



Remediation Guidance

Make sure it is an authorized change

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.


SubPattern Definitions

SubPattern Name: DCUserGrpChange

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

reptDevIpAddr IN (Group@PH_SYS_DEVICE_WINDOWS_SERVER)  AND eventType IN (Group@PH_SYS_EVENT_GroupMemberRemoved) AND targetUserGrp = "Administrator"

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

reptDevName, user,computer,domain,targetUser,targetUserGrp,targetDomain

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

 hostName = DCUserGrpChange.reptDevName,
 user = DCUserGrpChange.user,
 computer =,
 domain = DCUserGrpChange.domain,
 targetUser = DCUserGrpChange.targetUser,
 targetDomain = DCUserGrpChange.targetDomain,
targetUserGrp = DCUserGrpChange.targetUserGrp