disabled_kerberos_pre_authentication_discovery_with_get_aduser.yml

name: Disabled Kerberos Pre-Authentication Discovery With Get-ADUser
id: 114c6bfe-9406-11ec-bcce-acde48001122
version: 2
date: '2023-12-27'
author: Mauricio Velazco, Splunk
status: production
type: TTP
description: The following analytic utilizes PowerShell Script Block Logging (EventCode=4104)
  to identify the execution of the `Get-ADUser` commandlet with specific parameters.
  `Get-ADUser` is part of the Active Directory PowerShell module used to manage Windows
  Active Directory networks. As the name suggests, `Get-ADUser` is used to query for
  domain users. With the appropiate parameters, Get-ADUser allows adversaries to discover
  domain accounts with Kerberos Pre Authentication disabled.\ Red Teams and adversaries
  alike use may abuse Get-ADUSer to enumerate these accounts and attempt to crack
  their passwords offline.
data_source:
- Powershell Script Block Logging 4104
search: ' `powershell` EventCode=4104 (ScriptBlockText = "*Get-ADUser*" AND ScriptBlockText="*4194304*")
  | stats count min(_time)  as firstTime max(_time) as lastTime by Opcode Computer
  UserID EventCode ScriptBlockText | rename Computer as dest | `security_content_ctime(firstTime)`
  | `disabled_kerberos_pre_authentication_discovery_with_get_aduser_filter`'
how_to_implement: 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 search for accounts with
  Kerberos Pre Authentication disabled for legitimate purposes.
references:
- https://attack.mitre.org/techniques/T1558/004/
- https://m0chan.github.io/2019/07/31/How-To-Attack-Kerberos-101.html
- https://stealthbits.com/blog/cracking-active-directory-passwords-with-as-rep-roasting/
tags:
  analytic_story:
  - CISA AA23-347A
  - Active Directory Kerberos Attacks
  asset_type: Endpoint
  confidence: 90
  impact: 60
  message: Disabled Kerberos Pre-Authentication Discovery With Get-ADUser from $dest$
  mitre_attack_id:
  - T1558
  - T1558.004
  observable:
  - name: dest
    type: Endpoint
    role:
    - Victim
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - ScriptBlockText
  - Opcode
  - Computer
  - UserID
  - EventCode
  risk_score: 54
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1558.004/getaduser/get-aduser-powershell.log
    source: XmlWinEventLog:Microsoft-Windows-PowerShell/Operational
    sourcetype: xmlwineventlog