Windows PowerShell Script From WindowsApps Directory

SPLUNK detection rule by Michael Haag, Splunk · Apache-2.0

The following analytic identifies the execution of PowerShell scripts from the WindowsApps directory, which is a common technique used in malicious MSIX package execution. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process command lines and parent process paths. This activity is significant as adversaries have been observed using MSIX packages with embedded PowerShell scripts (particularly StartingScriptWrapper.ps1) to execute malicious code. If confirmed malicious, this could allow attackers to execute arbitrary code, establish persistence, or deliver malware while evading traditional detection mechanisms.

name: Windows PowerShell Script From WindowsApps Directory
id: 8c3d1f2e-7b4a-45e3-9d8f-6a2e4c9b1234
version: 4
creation_date: '2025-08-18'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: TTP
description: |-
    The following analytic identifies the execution of PowerShell scripts from the WindowsApps directory, which is a common technique used in malicious MSIX package execution.
    This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process command lines and parent process paths.
    This activity is significant as adversaries have been observed using MSIX packages with embedded PowerShell scripts (particularly StartingScriptWrapper.ps1) to execute malicious code.
    If confirmed malicious, this could allow attackers to execute arbitrary code, establish persistence, or deliver malware while evading traditional detection mechanisms.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |-
    | tstats `security_content_summariesonly`
      count min(_time) as firstTime
            max(_time) as lastTime

    FROM datamodel=Endpoint.Processes where

    (
        `process_powershell`
        OR
        `process_cmd`
    )
    AND
    (
        Processes.parent_process_path="*\\WindowsApps\\*"
        OR
        Processes.process IN ("*WindowsApps*-file *", "*WindowsApps*.ps1*")
    )

    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_script_from_windowsapps_directory_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 process execution information, including process paths and command lines. 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 applications installed via the Microsoft Store or MSIX packages may execute PowerShell scripts from the WindowsApps directory as part of their normal operation. Verify if the MSIX package is from a trusted source and signed by a trusted publisher before taking action. Look for additional suspicious activities like network connections to unknown domains or execution of known malicious payloads.
references:
    - https://redcanary.com/blog/threat-intelligence/msix-installers/
    - https://redcanary.com/threat-detection-report/techniques/installer-packages/
    - https://learn.microsoft.com/en-us/windows/msix/package/package-support-framework
    - https://attack.mitre.org/techniques/T1059/001/
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 ("$dest$") | 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: 7d
      latest_offset: "0"
    - name: Look for specific StartingScriptWrapper.ps1 execution
      search: '| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes where Processes.process_name="powershell.exe" AND Processes.process="*StartingScriptWrapper.ps1*" by Processes.dest Processes.process Processes.parent_process_name'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
finding:
    title: PowerShell script execution from WindowsApps directory detected on $dest$ by user $user$. This may indicate malicious MSIX package execution.
    entity:
        field: dest
        type: system
        score: 50
threat_objects:
    - field: process
      type: command
analytic_story:
    - MSIX Package Abuse
    - Malicious PowerShell
asset_type: Endpoint
mitre_attack_id:
    - T1059.001
    - T1204.002
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
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/msix_powershell/windows-sysmon.log
          sourcetype: XmlWinEventLog
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
      test_type: unit

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

24cb678d-684f-432d-b692-df9ffdb7e14c

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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