Detection rules › Splunk

Windows InstallUtil URL in Command Line

Status
production
Severity
medium
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
Michael Haag, Splunk
Source
github.com/splunk/security_content

The following analytic detects the use of Windows InstallUtil.exe with an HTTP or HTTPS URL in the command line. This is identified through Endpoint Detection and Response (EDR) telemetry, focusing on command-line executions containing URLs. This activity is significant as it may indicate an attempt to download and execute malicious code, potentially bypassing application control mechanisms. If confirmed malicious, this could lead to unauthorized code execution, privilege escalation, or persistent access within the environment. Analysts should review the parent process, network connections, file modifications, and related processes for further investigation.

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.

MITRE ATT&CK coverage

Telemetry coverage

Rule body

name: Windows InstallUtil URL in Command Line
id: 28e06670-43df-11ec-a569-acde48001122
version: 15
creation_date: '2021-11-12'
modification_date: '2026-07-14'
author: Michael Haag, Splunk
status: production
type: TTP
description: The following analytic detects the use of Windows InstallUtil.exe with an HTTP or HTTPS URL in the command line. This is identified through Endpoint Detection and Response (EDR) telemetry, focusing on command-line executions containing URLs. This activity is significant as it may indicate an attempt to download and execute malicious code, potentially bypassing application control mechanisms. If confirmed malicious, this could lead to unauthorized code execution, privilege escalation, or persistent access within the environment. Analysts should review the parent process, network connections, file modifications, and related processes for further investigation.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
    - Cisco Network Visibility Module Flow Data
search: |
    | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
    as lastTime from datamodel=Endpoint.Processes where
    `process_installutil`
    Processes.process IN ("*http://*","*https://*")
    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_url_in_command_line_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 as InstallUtil is not typically used to download remote files. Filter as needed based on Developers requirements.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.004/T1218.004.md
    - https://gist.github.com/DanielRTeixeira/0fd06ec8f041f34a32bf5623c6dd479d
finding:
    title: An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ passing a URL on the command-line.
    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 $user$ passing a URL on the command-line.
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
    - Cisco Network Visibility Module Analytics
asset_type: Endpoint
mitre_attack_id:
    - T1218.004
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint

Stages and Predicates

Stage 1: tstats

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
as lastTime from datamodel=Endpoint.Processes where
`process_installutil`
Processes.process IN ("*http://*","*https://*")
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_installutil_url_in_command_line_filter`

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Processes.original_file_nameeq
  • "InstallUtil.exe" corpus 21 (elastic 11, sigma 6, splunk 4)
field:"OriginalFileName" kind:eq
Processes.processin
  • "*http://*" corpus 23 (sigma 18, elastic 2, kusto 2, splunk 1)
  • "*https://*" corpus 23 (sigma 18, elastic 2, kusto 2, splunk 1)
field:"CommandLine" kind:in
Processes.process_nameeq
  • "installutil.exe" corpus 37 (elastic 32, splunk 5)
field:"process_name" kind:eq