get_aduser_with_powershell_script_block.yml

name: Get ADUser with PowerShell Script Block
id: 21432e40-04f4-11ec-b7e6-acde48001122
version: 3
date: '2024-05-29'
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*" | 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`'
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
tags:
  analytic_story:
  - Active Directory Discovery
  - CISA AA23-347A
  asset_type: Endpoint
  confidence: 50
  impact: 50
  message: Powershell process having commandline "get-aduser" for user enumeration
    on $dest$
  mitre_attack_id:
  - T1087.002
  - T1087
  observable:
  - name: dest
    type: Hostname
    role:
    - Victim
  - name: user
    type: User
    role:
    - Victim
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - EventCode
  - Message
  - ComputerName
  - User
  risk_score: 25
  security_domain: endpoint
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