Disabled Kerberos Pre-Authentication Discovery With Get-ADUser
Description
The following analytic detects the execution of the Get-ADUser
PowerShell cmdlet with parameters indicating a search for domain accounts with Kerberos Pre-Authentication disabled. It leverages PowerShell Script Block Logging (EventCode=4104) to identify this specific activity. This behavior is significant because discovering accounts with Kerberos Pre-Authentication disabled can allow adversaries to perform offline password cracking. If confirmed malicious, this activity could lead to unauthorized access to user accounts, potentially compromising sensitive information and escalating privileges within the network.
- Type: TTP
-
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2024-05-29
- Author: Mauricio Velazco, Splunk
- ID: 114c6bfe-9406-11ec-bcce-acde48001122
Annotations
ATT&CK
Kill Chain Phase
- Exploitation
NIST
- DE.CM
CIS20
- CIS 10
CVE
Search
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`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
| rename Computer as dest
| `security_content_ctime(firstTime)`
| `disabled_kerberos_pre_authentication_discovery_with_get_aduser_filter`
Macros
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.
Required fields
List of fields required to use this analytic.
- _time
- ScriptBlockText
- Opcode
- Computer
- UserID
- EventCode
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
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
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.
Reference
- https://attack.mitre.org/techniques/T1558/004/
- 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: 3