Windows InstallUtil Uninstall Option

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

The following analytic detects the use of the Windows InstallUtil.exe binary with the `/u` (uninstall) switch, which can execute code while bypassing application control. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names, parent processes, and command-line executions. This activity is significant because it can indicate an attempt to execute malicious code without administrative privileges. If confirmed malicious, an attacker could achieve code execution, potentially leading to further system compromise or persistence within the environment.

name: Windows InstallUtil Uninstall Option
id: cfa7b9ac-43f0-11ec-9b48-acde48001122
version: 14
creation_date: '2021-11-12'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: TTP
description: The following analytic detects the use of the Windows InstallUtil.exe binary with the `/u` (uninstall) switch, which can execute code while bypassing application control. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names, parent processes, and command-line executions. This activity is significant because it can indicate an attempt to execute malicious code without administrative privileges. If confirmed malicious, an attacker could achieve code execution, potentially leading to further system compromise or persistence within the environment.
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_installutil` Processes.process IN ("*/u*", "*uninstall*") NOT (Processes.process IN ("*C:\\WINDOWS\\CCM\\*")) NOT (Processes.parent_process_name IN ("Microsoft.SharePoint.Migration.ClientInstaller.exe")) 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_installutil_uninstall_option_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: Limited false positives should be present. Filter as needed by parent process or application.
references:
    - https://evi1cg.me/archives/AppLocker_Bypass_Techniques.html#menu_index_12
    - https://github.com/api0cradle/UltimateAppLockerByPassList/blob/master/md/Installutil.exe.md
    - https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.004/T1218.004.md
drilldown_searches:
    - name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search  user = "$user$" dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$user$" and "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") | 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"
finding:
    title: An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ performing an uninstall.
    entity:
        field: user
        type: user
        score: 50
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 50
          message: An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ performing an uninstall.
threat_objects:
    - field: parent_process_name
      type: parent_process_name
    - field: process_name
      type: process_name
analytic_story:
    - Living Off The Land
    - Compromised Windows Host
    - Signed Binary Proxy Execution InstallUtil
asset_type: Endpoint
mitre_attack_id:
    - T1218.004
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/T1218.004/atomic_red_team/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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06bfea00-f6f1-41ab-b9af-911c8ba76ca4

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Executable code, not a declarative rule

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Format & documentation suggestions

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