name: Rundll32 LockWorkStation
id: fa90f372-f91d-11eb-816c-acde48001122
version: 2
date: '2021-08-09'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: This search is to detect a suspicious rundll32 commandline to lock the
  workstation through command line. This technique was seen in CONTI leak tooling
  and script as part of its defense evasion. This technique is not a common practice
  to lock a screen and maybe a good indicator of compromise.
data_source:
- Sysmon Event ID 1
search:
  selection1:
    CommandLine: '*user32.dll,LockWorkStation*'
    Image|endswith: rundll32.exe
  condition: selection1
how_to_implement: To successfully implement this search, you need to be ingesting
  logs with the process name, parent process, and command-line executions from your
  endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the
  Sysmon TA. Tune and filter known instances where renamed rundll32.exe may be used.
known_false_positives: unknown
references:
- https://threadreaderapp.com/thread/1423361119926816776.html
tags:
  analytic_story:
  - Ransomware
  asset_type: Endpoint
  confidence: 50
  impact: 50
  message: process $process_name$ with cmdline $process$ in host $dest$
  mitre_attack_id:
  - T1218
  - T1218.011
  observable:
  - name: dest
    type: Hostname
    role:
    - Victim
  - name: SourceImage
    type: Process Name
    role:
    - Attacker
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  risk_score: 25
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/conti/conti_leak/windows-sysmon.log
    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
    sourcetype: xmlwineventlog