Detection: GetAdGroup with PowerShell Script Block

Updated Date: 2024-05-22 ID: e4c73d68-794b-468d-b4d0-dac1772bbae7 Author: Mauricio Velazco, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects the execution of the Get-AdGroup PowerShell cmdlet using PowerShell Script Block Logging (EventCode=4104). This cmdlet is used to enumerate all domain groups, which adversaries may exploit for situational awareness and Active Directory discovery. Monitoring this activity is crucial as it can indicate reconnaissance efforts within the network. If confirmed malicious, this behavior could lead to further exploitation, such as privilege escalation or lateral movement, by providing attackers with detailed information about the domain's group structure.

Search

1`powershell` EventCode=4104 ScriptBlockText = "*Get-ADGroup*" 
2| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer UserID 
3| rename Computer as dest, UserID as user 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `getadgroup_with_powershell_script_block_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Powershell Script Block Logging 4104	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Microsoft-Windows-PowerShell/Operational'`	N/A

Macros Used

Name	Value
powershell	`(source=WinEventLog:Microsoft-Windows-PowerShell/Operational OR source="XmlWinEventLog:Microsoft-Windows-PowerShell/Operational")`
getadgroup_with_powershell_script_block_filter	`search *`

getadgroup_with_powershell_script_block_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1069	Permission Groups Discovery	Discovery
T1069.002	Domain Groups	Discovery

KillChainPhase.EXPLOITAITON

NistCategory.DE_AE

Cis18Value.CIS_10

APT3

APT41

FIN13

TA505

Dragonfly

FIN7

Inception

Ke3chang

LAPSUS$

OilRig

ToddyCat

Turla

Volt Typhoon

Default Configuration

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

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Risk Event	False

This configuration file applies to all detections of type hunting.

Implementation

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.

Known False Positives

Administrators or power users may use this PowerShell commandlet for troubleshooting.

Associated Analytic Story

Active Directory Discovery

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
Domain group discovery enumeration using PowerShell on $dest$ by $user$	15	30	50

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-PowerShell/Operational`	`xmlwineventlog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-PowerShell/Operational`	`xmlwineventlog`

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: 3