Windows Explorer.exe Spawning PowerShell or Cmd

name: Windows Explorer.exe Spawning PowerShell or Cmd
id: 593854c5-2182-49dd-9f31-18ef697445b9
version: 2
date: '2025-05-02'
author: Michael Haag, AJ King, Splunk, Jesse Hunter, Splunk Community Contributor
status: production
type: Hunting
description: This detection identifies instances where Windows Explorer.exe spawns PowerShell or cmd.exe processes, particularly focusing on executions initiated by LNK files. This behavior is associated with the ZDI-CAN-25373 Windows shortcut zero-day vulnerability, where specially crafted LNK files are used to trigger malicious code execution through cmd.exe or powershell.exe. This technique has been actively exploited by multiple APT groups in targeted attacks through both HTTP and SMB delivery methods.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_path="*\\explorer.exe" `process_powershell` OR `process_cmd`  by  Processes.dest Processes.process_current_directory Processes.process_path Processes.process Processes.original_file_name Processes.parent_process Processes.parent_process_name Processes.parent_process_path Processes.parent_process_guid Processes.parent_process_id Processes.process_guid Processes.process_id Processes.user | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)`| `security_content_ctime(lastTime)` | `windows_explorer_exe_spawning_powershell_or_cmd_filter`'
how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: Some legitimate user actions may trigger Explorer.exe to spawn PowerShell or cmd.exe, such as right-clicking and selecting "Open PowerShell window here" or similar options. Filter as needed based on your environment's normal behavior patterns.
references:
    - https://www.zerodayinitiative.com/advisories/ZDI-CAN-25373/
    - https://www.trendmicro.com/en_us/research/25/c/windows-shortcut-zero-day-exploit.html
tags:
    analytic_story:
        - ZDI-CAN-25373 Windows Shortcut Exploit Abused as Zero-Day
    asset_type: Endpoint
    mitre_attack_id:
        - T1059.001
        - T1204.002
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059.001/encoded_powershell/explorer_spawns_windows-sysmon.log
          sourcetype: XmlWinEventLog
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational