Try in Splunk Security Cloud

Description

The following analytic detects the execution of the PowerView PowerShell cmdlet Get-NetUser with the -PreauthNotRequire parameter, leveraging Event ID 4104. This method identifies attempts to query Active Directory user accounts that do not require Kerberos preauthentication. Monitoring this activity is crucial as it can indicate reconnaissance efforts by an attacker to identify potentially vulnerable accounts. If confirmed malicious, this behavior could lead to further exploitation, such as unauthorized access or privilege escalation within the network.

  • Type: Hunting

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

  • Last Updated: 2024-05-27
  • Author: Teoderick Contreras, Splunk
  • ID: cf056b65-44b2-4d32-9172-d6b6f081a376

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1087 Account Discovery Discovery
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


1
2
3
4
5
6



`powershell` EventCode=4104  ScriptBlockText = "*Get-NetUser*" ScriptBlockText = "*-PreauthNotRequire*" 
| rename Computer as dest, UserID as user 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText dest user 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_account_discovery_with_netuser_preauthnotrequire_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_account_discovery_with_netuser_preauthnotrequire_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
  • dest
  • EventCode
  • 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 may leverage PowerView for legitimate purposes, filter as needed.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
15.0 30 50 A user dicovery using powerview commandlet Get-NetUser with PreauthNotRequire parameter 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: 2