Detection: Windows Default Group Policy Object Modified with GPME

Description

The following analytic detects modifications to default Group Policy Objects (GPOs) using the Group Policy Management Editor (GPME). It leverages the Endpoint data model to identify processes where mmc.exe executes gpme.msc with specific GUIDs related to default GPOs. This activity is significant because default GPOs, such as the Default Domain Controllers Policy and Default Domain Policy, are critical for enforcing security policies across the domain. If malicious, such modifications could allow an attacker to gain further access, establish persistence, or deploy malware across numerous hosts, severely compromising the network's security.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=mmc.exe (Processes.process =*gpme.msc*) AND (Processes.process = "*31B2F340-016D-11D2-945F-00C04FB984F9*" OR Processes.process = "*6AC1786C-016F-11D2-945F-00C04fB984F9*"  ) by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `windows_default_group_policy_object_modified_with_gpme_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'xmlwineventlog'	'XmlWinEventLog:Security'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

The default Group Policy Objects within an AD network may be legitimately updated for administrative operations, filter as needed.

Associated Analytic Story

• Active Directory Privilege Escalation

• Sneaky Active Directory Persistence Tricks

Risk Based Analytics (RBA)

References

• https://attack.mitre.org/techniques/T1484/

• https://attack.mitre.org/techniques/T1484/001

• https://www.trustedsec.com/blog/weaponizing-group-policy-objects-access/

• https://adsecurity.org/?p=2716

• https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/dn265969(v=ws.11)

Detection Testing

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 4