Domain Controller User or Group Modification

Rule ID

PH_Rule_Change_3

Default Status

Enabled

Description

Detects user/group configuration in a domain controller. This rule would trigger on all changes made by any person. To prevent false positives, a restriction on the user attribute should be made by excluding the domain administrators.

Severity

MITRE ATT&CK® Tactics

Persistence

Persistence consists of techniques that adversaries use to keep access to systems across restarts, changed credentials, and other interruptions that could cut off their access. Techniques used for persistence include any access, action, or configuration changes that let them maintain their foothold on systems, such as replacing or hijacking legitimate code or adding startup code.

https://attack.mitre.org/tactics/TA0003

MITRE ATT&CK® Techniques

T1098.001

Account Manipulation: Additional Cloud Credentials

Adversaries may add adversary-controlled credentials for Azure Service Principals in addition to existing legitimate credentials to maintain persistent access to victim Azure accounts. Azure Service Principals support both password and certificate credentials. With sufficient permissions, there are a variety of ways to add credentials including the Azure Portal, Azure command line interface, and Azure powershell.

https://attack.mitre.org/techniques/T1098/001

Impacts

Application

Data Source

Windows Security Log via OMI or FortiSIEM Agent

Detection

Correlation

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.

DCUserGrpChange

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_APP_DOMAIN_CONTROLLER)  AND  eventType IN ( Group@PH_SYS_EVENT_AccountChanged)

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,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 = DCUserGrpChange.computer,
 domain = DCUserGrpChange.domain,
 targetUser = DCUserGrpChange.targetUser,
 targetDomain = DCUserGrpChange.targetDomain

FortiSIEM Rules