Windows PowerShell FakeCAPTCHA Clipboard Execution

name: Windows PowerShell FakeCAPTCHA Clipboard Execution
id: d81d4d3d-76b5-4f21-ab51-b17d5164c106
version: 7
date: '2026-03-10'
author: Michael Haag, Splunk
status: production
type: TTP
description: |
    This detection identifies potential FakeCAPTCHA/ClickFix clipboard hijacking campaigns by looking for PowerShell execution with hidden window parameters and distinctive strings related to fake CAPTCHA verification. These campaigns use social engineering to trick users into pasting malicious PowerShell commands from their clipboard, typically delivering information stealers or remote access trojans.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
    - Cisco Network Visibility Module Flow Data
search: |-
    | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
      WHERE `process_powershell`
        AND
        Processes.process="*-w*h*"
        AND
        ( (Processes.process IN ("*robot*", "*captcha*", "*verify*", "*security check*", "*complete verification*"))
        OR
        ( (Processes.process IN ("*iwr *", "*Invoke-WebRequest*", "*wget *", "*curl *", "*Net.WebClient*", "*DownloadString*", "*[Convert]::FromBase64String*"))
        AND
        (Processes.process IN ("*iex*", "*Invoke-Expression*"))
        AND
        (Processes.process IN ("*click*", "*verify*", "*check*", "*human*", "*bot*", "*token*", "*challenge*")) )
        OR
        ( Processes.process="*clipboard*"
        AND
        Processes.process="*iex*"
        AND
        (Processes.process="*FromBase64String*"
        OR
        Processes.process="*decode*") ) )
      BY Processes.action Processes.dest Processes.original_file_name
         Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
         Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
         Processes.process Processes.process_exec Processes.process_guid
         Processes.process_hash Processes.process_id Processes.process_integrity_level
         Processes.process_name Processes.process_path Processes.user
         Processes.user_id Processes.vendor_product
    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_powershell_fakecaptcha_clipboard_execution_filter`
how_to_implement: To successfully implement this search, you need to be ingesting logs with the process name, process path, and command-line executions from your endpoints. If you are using Sysmon, you must have at least Sysmon version 6.0.4 with EventID 1 configured. The full command line arguments are necessary for proper detection.
known_false_positives: Legitimate PowerShell commands that use hidden windows for automation tasks may trigger this detection. The search specifically looks for patterns typical of FakeCAPTCHA campaigns. You may need to add additional exclusions for legitimate administrative activities in your environment by modifying the filter macro.
references:
    - https://urlhaus.abuse.ch/
    - https://www.proofpoint.com/us/blog/threat-insight/security-brief-clickfix-social-engineering-technique-floods-threat-landscape
    - https://reliaquest.com/blog/using-captcha-for-compromise/
    - https://attack.mitre.org/techniques/T1204/001/
    - https://github.com/MHaggis/ClickGrab
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: A potential FakeCAPTCHA/ClickFix campaign execution was detected on $dest$ running a PowerShell command with hidden window and suspicious verification strings typical of social engineering attacks.
    risk_objects:
        - field: dest
          type: system
          score: 50
    threat_objects:
        - field: process
          type: process
tags:
    analytic_story:
        - Scattered Lapsus$ Hunters
        - Fake CAPTCHA Campaigns
        - Cisco Network Visibility Module Analytics
        - Interlock Ransomware
        - NetSupport RMM Tool Abuse
    asset_type: Endpoint
    mitre_attack_id:
        - T1059.001
        - T1204.001
        - T1059.003
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
    cve: []
tests:
    - name: True Positive Test - Sysmon
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059.001/atomic_red_team/captcha_windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
    - name: True Positive Test - Cisco NVM
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/cisco_network_visibility_module/cisco_nvm_flowdata/nvm_flowdata.log
          source: not_applicable
          sourcetype: cisco:nvm:flowdata