---
title: "Disabled Kerberos Pre-Authentication Discovery With Get-ADUser"
excerpt: "Steal or Forge Kerberos Tickets, AS-REP Roasting"
categories:
  - Endpoint
last_modified_at: 2022-02-22
toc: true
toc_label: ""
tags:
  - Steal or Forge Kerberos Tickets
  - Credential Access
  - AS-REP Roasting
  - Credential Access
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
---



[Try in Splunk Security Cloud](https://www.splunk.com/en_us/cyber-security.html){: .btn .btn--success}

#### 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.

- **Type**: [TTP](https://github.com/splunk/security_content/wiki/Detection-Analytic-Types)
- **Product**: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- **Datamodel**: 
- **Last Updated**: 2022-02-22
- **Author**: Mauricio Velazco, Splunk
- **ID**: 114c6bfe-9406-11ec-bcce-acde48001122


#### [ATT&CK](https://attack.mitre.org/)

| ID             | Technique        |  Tactic             |
| -------------- | ---------------- |-------------------- |
| [T1558](https://attack.mitre.org/techniques/T1558/) | Steal or Forge Kerberos Tickets | Credential Access |

| [T1558.004](https://attack.mitre.org/techniques/T1558/004/) | AS-REP Roasting | Credential Access |

#### Search

```
 `powershell` EventCode=4104 (Message = "*Get-ADUser*" AND Message="*4194304*") 
| stats count min(_time)  as firstTime max(_time) as lastTime by EventCode Message ComputerName User 
| `security_content_ctime(firstTime)` 
| `disabled_kerberos_pre_authentication_discovery_with_get_aduser_filter`
```

#### Macros
The SPL above uses the following Macros:
* [powershell](https://github.com/splunk/security_content/blob/develop/macros/powershell.yml)
* [security_content_ctime](https://github.com/splunk/security_content/blob/develop/macros/security_content_ctime.yml)

Note that `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.

#### Required field
* _time
* EventCode
* Message
* ComputerName
* User


#### 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.

#### Associated Analytic story
* [Active Directory Kerberos Attacks](/stories/active_directory_kerberos_attacks)


#### Kill Chain Phase
* Privilege Escalation



#### RBA

| Risk Score  | Impact      | Confidence   | Message      |
| ----------- | ----------- |--------------|--------------|
| 54.0 | 60 | 90 | Disabled Kerberos Pre-Authentication Discovery With Get-ADUser from $dest$ |


Note that risk score is calculated base on the following formula: `(Impact * Confidence)/100`



#### Reference

* [https://attack.mitre.org/techniques/T1558/004/](https://attack.mitre.org/techniques/T1558/004/)
* [https://m0chan.github.io/2019/07/31/How-To-Attack-Kerberos-101.html](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/](https://stealthbits.com/blog/cracking-active-directory-passwords-with-as-rep-roasting/)



#### Test Dataset
Replay any dataset to Splunk Enterprise by using our [`replay.py`](https://github.com/splunk/attack_data#using-replaypy) tool or the [UI](https://github.com/splunk/attack_data#using-ui).
Alternatively you can replay a dataset into a [Splunk Attack Range](https://github.com/splunk/attack_range#replay-dumps-into-attack-range-splunk-server)

* [https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1558.004/getaduser/windows-powershell.log](https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1558.004/getaduser/windows-powershell.log)



[*source*](https://github.com/splunk/security_content/tree/develop/detections/endpoint/disabled_kerberos_pre-authentication_discovery_with_get-aduser.yml) \| *version*: **1**