Get ADUser with PowerShell Script Block

Name:Get ADUser with PowerShell Script Block
id:21432e40-04f4-11ec-b7e6-acde48001122
version:10
date:None
author:Teoderick Contreras, Mauricio Velazco, Splunk
status:production
type:Hunting
Description:The following analytic detects the execution of the `Get-AdUser` PowerShell cmdlet, which is used to enumerate all domain users. It leverages PowerShell Script Block Logging (EventCode=4104) to identify instances where this command is executed with a filter. This activity is significant as it may indicate an attempt by adversaries or Red Teams to gather information about domain users for situational awareness and Active Directory discovery. If confirmed malicious, this behavior could lead to further reconnaissance and potential exploitation of user accounts within the domain.
Data_source:

• -Powershell Script Block Logging 4104

search:`powershell` EventCode=4104 ScriptBlockText = "*get-aduser*" ScriptBlockText = "*-filter*"

| fillnull

| stats count min(_time) as firstTime max(_time) as lastTime
BY dest signature signature_id
user_id vendor_product EventID
Guid Opcode Name
Path ProcessID ScriptBlockId
ScriptBlockText

| `security_content_ctime(firstTime)`

| `security_content_ctime(lastTime)`

| `get_aduser_with_powershell_script_block_filter`

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.
References:
  -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
drilldown_searches:
  :
analytic_story:['Active Directory Discovery', 'CISA AA23-347A']

asset_type:Endpoint

mitre_attack_id:['T1087.002']

product:['Splunk Enterprise', 'Splunk Enterprise Security', 'Splunk Cloud']

category:endpoint

security_domain:endpoint

tags:

tests:
 name:'True Positive Test'
 attack_data:
  data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1087.002/AD_discovery/aduser_powershell.log
  source: XmlWinEventLog:Microsoft-Windows-PowerShell/Operational
  sourcetype: XmlWinEventLog
 test_type:'unit'
manual_test:None