Kerberos Pre-Authentication Flag Disabled with PowerShell
Description
The following analytic utilizes PowerShell Script Block Logging (EventCode=4104) to identify the execution of the Set-ADAccountControl
commandlet with specific parameters. Set-ADAccountControl
is part of the Active Directory PowerShell module used to manage Windows Active Directory networks. As the name suggests, Set-ADAccountControl
is used to modify User Account Control values for an Active Directory domain account. With the appropiate parameters, Set-ADAccountControl allows adversaries to disable Kerberos Pre-Authentication for an account to to easily perform a brute force attack against the user'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
-
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-03-22
- Author: Mauricio Velazco, Splunk
- ID: 59b51620-94c9-11ec-b3d5-acde48001122
Annotations
ATT&CK
Kill Chain Phase
- Exploitation
NIST
CIS20
CVE
Search
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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
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `kerberos_pre_authentication_flag_disabled_with_powershell_filter`
Macros
The SPL above uses the following Macros:
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
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 $dest$ |
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
- 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://stealthbits.com/blog/cracking-active-directory-passwords-with-as-rep-roasting/
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: 2