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Description

The following analytic detects the use of the Set-ADAccountControl PowerShell cmdlet with parameters that disable Kerberos Pre-Authentication. It leverages PowerShell Script Block Logging (EventCode=4104) to identify this specific command execution. Disabling Kerberos Pre-Authentication is significant because it allows adversaries to perform offline brute force attacks against user passwords using the AS-REP Roasting technique. If confirmed malicious, this activity could enable attackers to escalate privileges or maintain persistence within an Active Directory environment, posing a severe security risk.

  • Type: TTP

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

  • Last Updated: 2024-05-12
  • Author: Mauricio Velazco, Splunk
  • ID: 59b51620-94c9-11ec-b3d5-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1558 Steal or Forge Kerberos Tickets Credential Access
T1558.004 AS-REP Roasting Credential Access
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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`powershell` EventCode=4104 (ScriptBlockText = "*Set-ADAccountControl*" AND ScriptBlockText="*DoesNotRequirePreAuth:$true*") 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer user_id 
| rename Computer as dest 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `kerberos_pre_authentication_flag_disabled_with_powershell_filter`

Macros

The SPL above uses the following Macros:

:information_source: kerberos_pre-authentication_flag_disabled_with_powershell_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
  • ScriptBlockText
  • Computer
  • user_id

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

Although unlikely, Administrators may need to set this flag for legitimate purposes.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
45.0 50 90 Kerberos Pre Authentication was Disabled using PowerShell on $dest$

:information_source: 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

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

source | version: 3