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.
- Type: TTP
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-05-03
- Author: Mauricio Velazco, Splunk
- ID: 114c6bfe-9406-11ec-bcce-acde48001122
Kill Chain Phase
1 2 3 4 `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 | `security_content_ctime(firstTime)` | `disabled_kerberos_pre_authentication_discovery_with_get_aduser_filter`
The SPL above uses the following Macros:
disabled_kerberos_pre-authentication_discovery_with_get-aduser_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
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/184.108.40.206/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.
Associated Analytic Story
|54.0||60||90||Disabled Kerberos Pre-Authentication Discovery With Get-ADUser from $dest$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 2