Get ADUser with PowerShell Script Block

Try in Splunk Security Cloud

Description

The following analytic utilizes PowerShell Script Block Logging (EventCode=4104) to identify the execution of the Get-AdGUser commandlet. The Get-AdUser commandlet is used to return a list of all domain users. Red Teams and adversaries may leverage this commandlet to enumerate domain groups for situational awareness and Active Directory Discovery.

• Type: Hunting

• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

• Last Updated: 2022-09-13
• Author: Teoderick Contreras, Mauricio Velazco, Splunk
• ID: 21432e40-04f4-11ec-b7e6-acde48001122

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1087.002	Domain Account	Discovery

T1087

Account Discovery

Discovery

Kill Chain Phase

• Exploitation

NIST

• DE.AE

CIS20

• CIS 10

CVE

Search

`powershell` EventCode=4104 ScriptBlockText = "*get-aduser*" ScriptBlockText = "*-filter*" 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer UserID 
| rename Computer as dest, UserID as user
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `get_aduser_with_powershell_script_block_filter`

Macros

The SPL above uses the following Macros:

• powershell
• security_content_ctime

get_aduser_with_powershell_script_block_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
• EventCode
• Message
• ComputerName
• User

How To Implement

The following Hunting analytic requires PowerShell operational logs to be imported. Modify the powershell macro as needed to match the sourcetype or add index. This analytic is specific to 4104, or PowerShell Script Block Logging.

Known False Positives

Administrators or power users may use this command for troubleshooting.

Associated Analytic Story

• Active Directory Discovery

RBA

Risk Score	Impact	Confidence	Message
25.0	50	50	Powershell process having commandline "get-aduser" for user enumeration on $dest$

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://www.blackhillsinfosec.com/red-blue-purple/
• https://attack.mitre.org/techniques/T1087/002/
• https://docs.microsoft.com/en-us/powershell/module/activedirectory/get-aduser?view=windowsserver2019-ps

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

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