Detection rules › Splunk

Windows Impair Defense Add Xml Applocker Rules

Status
production
Group by
IntegrityLevel, command_line, computer_name, event_action, original_file_name, parent_command_line, parent_process_guid, parent_process_id, parent_process_name, process_guid, process_hash, process_id, process_name, user, user_id, vendor_product
Author
Teoderick Contreras, Splunk
Source
github.com/splunk/security_content

The following analytic detects the use of a PowerShell commandlet to import an AppLocker XML policy. This behavior is identified by monitoring processes that execute the "Import-Module Applocker" and "Set-AppLockerPolicy" commands with the "-XMLPolicy" parameter. This activity is significant because it can indicate an attempt to disable or bypass security controls, as seen in the Azorult malware. If confirmed malicious, this could allow an attacker to disable antivirus products, leading to further compromise and persistence within the environment.

Known false positives

  • Administrators may execute this command that may cause some false positive.

MITRE ATT&CK coverage

TacticTechniques
Defense Impairment

Telemetry coverage

Rule body

name: Windows Impair Defense Add Xml Applocker Rules
id: 467ed9d9-8035-470e-ad5e-ae5189283033
version: 10
creation_date: '2022-06-28'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Hunting
description: The following analytic detects the use of a PowerShell commandlet to import an AppLocker XML policy. This behavior is identified by monitoring processes that execute the "Import-Module Applocker" and "Set-AppLockerPolicy" commands with the "-XMLPolicy" parameter. This activity is significant because it can indicate an attempt to disable or bypass security controls, as seen in the Azorult malware. If confirmed malicious, this could allow an attacker to disable antivirus products, leading to further compromise and persistence within the environment.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |-
    | tstats `security_content_summariesonly` values(Processes.process) as process min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
      WHERE `process_powershell`
        AND
        Processes.process="*Import-Module Applocker*"
        AND
        Processes.process="*Set-AppLockerPolicy *"
        AND
        Processes.process="* -XMLPolicy *"
      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_impair_defense_add_xml_applocker_rules_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: Administrators may execute this command that may cause some false positive.
references:
    - https://app.any.run/tasks/a6f2ffe2-e6e2-4396-ae2e-04ea0143f2d8/
analytic_story:
    - Azorult
asset_type: Endpoint
mitre_attack_id:
    - T1685
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint

Stages and Predicates

Stage 1: tstats

| tstats `security_content_summariesonly` values(Processes.process) as process min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
  WHERE `process_powershell`
    AND
    Processes.process="*Import-Module Applocker*"
    AND
    Processes.process="*Set-AppLockerPolicy *"
    AND
    Processes.process="* -XMLPolicy *"
  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

Stage 2: search

| `drop_dm_object_name(Processes)`

Stage 3: search

| `security_content_ctime(firstTime)`

Stage 4: search

| `security_content_ctime(lastTime)`

Stage 5: search

| `windows_impair_defense_add_xml_applocker_rules_filter`

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Processes.original_file_nameeq
  • "PowerShell.EXE" corpus 138 (sigma 84, splunk 30, elastic 24)
  • "powershell_ise.EXE" corpus 51 (splunk 30, sigma 18, elastic 3)
  • "pwsh.dll" corpus 112 (sigma 79, splunk 30, elastic 3)
field:"OriginalFileName" kind:eq
Processes.processeq
  • "* -XMLPolicy *"
  • "*Import-Module Applocker*"
  • "*Set-AppLockerPolicy *"
field:"CommandLine" kind:eq
Processes.process_nameeq
  • "powershell.exe" corpus 184 (elastic 140, splunk 44)
  • "powershell_ise.exe" corpus 52 (splunk 29, elastic 23)
  • "pwsh.exe" corpus 77 (elastic 48, splunk 29)
field:"process_name" kind:eq