Windows Admon Default Group Policy Object Modified
Description
The following analytic leverages Splunks Admon to identify the modification of a default Group Policy Object. A fresh installation of an Active Directory network will typically contain two default group policy objects Default Domain Controllers Policy
and Default Domain Policy
. The default domain controllers policy is used to enforce and set policies to all the domain controllers within the domain environment. The default domain policy is linked to all users and computers by default. An adversary who has obtained privileged access to an Active Directory network may modify the default group policy objects to obtain further access, deploy persistence or execute malware across a large number of hosts. Security teams should monitor the modification of the default GPOs.
- Type: TTP
-
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2023-03-29
- Author: Mauricio Velazco, Splunk
- ID: 83458004-db60-4170-857d-8572f16f070b
Annotations
ATT&CK
Kill Chain Phase
- Exploitation
NIST
- DE.CM
CIS20
- CIS 10
CVE
Search
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`admon` admonEventType=Update objectCategory="CN=Group-Policy-Container,CN=Schema,CN=Configuration,DC=*" (displayName="Default Domain Policy" OR displayName="Default Domain Controllers Policy")
| stats min(_time) as firstTime max(_time) as lastTime values(gPCFileSysPath) by dcName, displayName
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_admon_default_group_policy_object_modified_filter`
Macros
The SPL above uses the following Macros:
windows_admon_default_group_policy_object_modified_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Required fields
List of fields required to use this analytic.
- _time
- admonEventType
- objectCategory
- displayName
- gPCFileSysPath
- dcName
How To Implement
To successfully implement this search, you need to be monitoring Active Directory logs using Admon. Details can be found here https://docs.splunk.com/Documentation/SplunkCloud/8.1.2101/Data/MonitorActiveDirectory
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
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
50.0 | 100 | 50 | A default domain group policy was updated on $dcName$ |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
Reference
- 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://docs.splunk.com/Documentation/SplunkCloud/8.1.2101/Data/MonitorActiveDirectory
Test Dataset
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 | version: 1