Detection: Windows InstallUtil Uninstall Option with Network

Updated Date: 2025-02-10 ID: 1a52c836-43ef-11ec-a36c-acde48001122 Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies the use of Windows InstallUtil.exe making a remote network connection using the /u (uninstall) switch. This detection leverages Endpoint Detection and Response (EDR) telemetry, focusing on process and network activity data. This behavior is significant as it may indicate an attempt to download and execute code while bypassing application control mechanisms. If confirmed malicious, this activity could allow an attacker to execute arbitrary code, potentially leading to system compromise, data exfiltration, or further lateral movement within the network.

 1
 2| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes where `process_installutil` Processes.process IN ("*/u*", "*uninstall*") by _time span=1h  Processes.user Processes.process_id Processes.process_name Processes.dest Processes.process_path Processes.process Processes.parent_process_name 
 3| `drop_dm_object_name(Processes)` 
 4| `security_content_ctime(firstTime)` 
 5| `security_content_ctime(lastTime)` 
 6| join  process_id [
 7| tstats `security_content_summariesonly` count FROM datamodel=Network_Traffic.All_Traffic where All_Traffic.dest_port != 0 by All_Traffic.process_id All_Traffic.dest All_Traffic.dest_port 
 8| `drop_dm_object_name(All_Traffic)` 
 9| rename dest as C2 ] 
10| table _time user dest parent_process_name process_name process_path process process_id dest_port C2 
11| `windows_installutil_uninstall_option_with_network_filter`

Data Source

Name Platform Sourcetype Source
Sysmon EventID 1 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Sysmon EventID 3 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Name Value
process_installutil (Processes.process_name=installutil.exe OR Processes.original_file_name=InstallUtil.exe)
windows_installutil_uninstall_option_with_network_filter search *
windows_installutil_uninstall_option_with_network_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1218.004 InstallUtil Defense Evasion
Exploitation
DE.CM
CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

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 as InstallUtil is not typically used to download remote files. Filter as needed based on Developers requirements.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ performing an uninstall.

Risk Object Risk Object Type Risk Score Threat Objects
dest system 80 process_name, parent_process_name
user user 80 process_name, parent_process_name

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 9