Suspicious Workstation Locking through Rundll32 (via process_creation)

title: Suspicious Workstation Locking through Rundll32 (via process_creation)
id: f86813bf-996d-52cb-98da-9753ae9e277d
status: stable
description: This rule detects an anomalous call to the user32.dll function that locks the user workstation
references:
    - https://app.any.run/tasks/2aef9c63-f944-4763-b3ef-81eee209d128/
author: Huntrule Team
date: 2026-02-03
tags:
    - attack.stealth
    - attack.defense-evasion
    - attack.t1218.011
logsource:
    category: process_creation
    product: windows
detection:
    selection_call_img:
        - Image|endswith: '\rundll32.exe'
        - OriginalFileName: 'RUNDLL32.EXE'
    selection_call_parent:
        ParentImage|endswith: '\cmd.exe'
    selection_call_cli:
        CommandLine|contains: 'user32.dll,'
    selection_function:
        CommandLine|contains: 'LockWorkStation'
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium