---
title: "Kerberos Pre-Authentication Flag Disabled in UserAccountControl"
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 leverages Windows Security Event 4738, `A user account was changed`, to identify a change performed on a domain user object that disables Kerberos Pre-Authentication. Disabling the Pre Authentication flag in the UserAccountControl property allows an adversary to easily perform a brute force attack against the user&#39;s password offline leveraging the ASP REP Roasting technique. Red Teams and adversaries alike who have obtained privileges in an Active Directory network may use this technique as a backdoor or a way to escalate privileges.

- **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**: 0cb847ee-9423-11ec-b2df-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

```
 `wineventlog_security` EventCode=4738 MSADChangedAttributes="*Don't Require Preauth' - Enabled*" 
| table EventCode, Account_Name, Security_ID, MSADChangedAttributes 
| `kerberos_pre_authentication_flag_disabled_in_useraccountcontrol_filter`
```

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

Note that `kerberos_pre-authentication_flag_disabled_in_useraccountcontrol_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
* Account_Name
* Security_ID
* MSADChangedAttributes


#### How To Implement
To successfully implement this search, you need to be ingesting Domain Controller events. The Advanced Security Audit policy setting `User Account Management` within `Account Management` needs to be enabled.

#### Known False Positives
Unknown.

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


#### Kill Chain Phase
* Intrusion
* Privilege Escalation



#### RBA

| Risk Score  | Impact      | Confidence   | Message      |
| ----------- | ----------- |--------------|--------------|
| 45.0 | 50 | 90 | Kerberos Pre Authentication was Disabled for $Account_Name$ |


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



#### Reference

* [https://docs.microsoft.com/en-us/troubleshoot/windows-server/identity/useraccountcontrol-manipulate-account-properties](https://docs.microsoft.com/en-us/troubleshoot/windows-server/identity/useraccountcontrol-manipulate-account-properties)
* [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/powershell/windows-security.log](https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1558.004/powershell/windows-security.log)



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