splunk_escuHunting

Windows Account Discovery With NetUser PreauthNotRequire

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.

Detection Query

`powershell` EventCode=4104  ScriptBlockText = "*Get-NetUser*" ScriptBlockText = "*-PreauthNotRequire*"
  | fillnull
  | stats count min(_time) as firstTime max(_time) as lastTime
    BY dest signature signature_id
       user_id vendor_product EventID
       Guid Opcode Name
       Path ProcessID ScriptBlockId
       ScriptBlockText
  | `security_content_ctime(firstTime)`
  | `security_content_ctime(lastTime)`
  | `windows_account_discovery_with_netuser_preauthnotrequire_filter`

Author

Teoderick Contreras, Splunk

Data Sources

Powershell Script Block Logging 4104

References

https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-347a

Raw Content

name: Windows Account Discovery With NetUser PreauthNotRequire
id: cf056b65-44b2-4d32-9172-d6b6f081a376
version: 9
creation_date: '2024-01-10'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Hunting
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.
data_source:
    - Powershell Script Block Logging 4104
search: |-
    `powershell` EventCode=4104  ScriptBlockText = "*Get-NetUser*" ScriptBlockText = "*-PreauthNotRequire*"
      | fillnull
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY dest signature signature_id
           user_id vendor_product EventID
           Guid Opcode Name
           Path ProcessID ScriptBlockId
           ScriptBlockText
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `windows_account_discovery_with_netuser_preauthnotrequire_filter`
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://help.splunk.com/en/security-offerings/splunk-user-behavior-analytics/get-data-in/5.4.1/add-other-data-to-splunk-uba/configure-powershell-logging-to-see-powershell-anomalies-in-splunk-uba.=
known_false_positives: Administrators may leverage PowerView for legitimate purposes, filter as needed.
references:
    - https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-347a
analytic_story:
    - CISA AA23-347A
asset_type: Endpoint
mitre_attack_id:
    - T1087
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1087/powerview_get_netuser_preauthnotrequire/get-netuser-not-require-pwh.log
          source: XmlWinEventLog:Microsoft-Windows-PowerShell/Operational
          sourcetype: XmlWinEventLog
      test_type: unit