Windows PowerShell Module File Created

name: Windows PowerShell Module File Created
id: ef018634-8999-4854-9344-bde9593468e7
version: 2
creation_date: '2021-09-02'
modification_date: '2026-05-13'
author: Raven Tait, Splunk
status: production
type: Anomaly
description: |-
    Detects the creation of a DLL within the various PowerShell module directories.
    This can indicate a new module being installed, attempts at ScriptBlock smuggling, or other malicious PowerShell activity utilizing modules.
    False positives could include installation of legitimate modules.
data_source:
    - Sysmon EventID 11
search: |-
    | tstats `security_content_summariesonly`
      count min(_time) as firstTime
            max(_time) as lastTime
    
    from datamodel=Endpoint.Filesystem where
    
    Filesystem.action="created"
    Filesystem.file_path="*\\WindowsPowerShell\\Modules\\*.dll"
    Filesystem.file_name="*.dll"
    
    by Filesystem.dest Filesystem.file_create_time Filesystem.process_path
       Filesystem.process_guid Filesystem.process_id Filesystem.file_path Filesystem.file_name
       Filesystem.user Filesystem.vendor_product Filesystem.action
    
    | `drop_dm_object_name(Filesystem)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_powershell_module_file_created_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: Legitimate installation of approved PowerShell modules may trigger this detection. Verify module sources to reduce false positives.
references:
    - https://bc-security.org/scriptblock-smuggling/
    - https://github.com/BC-SECURITY/ScriptBlock-Smuggling
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: PowerShell module DLL created at $file_path$ on $dest$.
threat_objects:
    - field: file_path
      type: file_path
analytic_story:
    - Malicious PowerShell
    - Windows Persistence Techniques
asset_type: Endpoint
mitre_attack_id:
    - T1129
    - T1059.001
    - T1574
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint