Windows InstallUtil.exe Downloading Files via HTTP/FTP

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1218System Binary Proxy Execution
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies process executions of InstallUtil.exe where the command line includes HTTP/HTTPS or FTP URLs, indicating an attempt to download external content. Attackers can use InstallUtil.exe to blend malicious activity into legitimate-looking .NET tooling behavior. The detection relies on process creation telemetry, specifically the executable path or metadata and the process command line containing URL schemes.

Reporting behind it

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Windows InstallUtil.exe Downloading Files via HTTP/FTP

Pivot detection · T1218 · 9 related

Changelog

v2

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-installutil-exe-used-to-download-remote-files-75edd216

title: Windows InstallUtil.exe Downloading Files via HTTP/FTP
id: 0d5f1528-2fcf-4eaa-a598-e515e9542300
status: test
description: This rule identifies process executions of InstallUtil.exe where the command line includes HTTP/HTTPS or FTP URLs, indicating an attempt to download external content. Attackers can use InstallUtil.exe to blend malicious activity into legitimate-looking .NET tooling behavior. The detection relies on process creation telemetry, specifically the executable path or metadata and the process command line containing URL schemes.
references:
  - https://github.com/LOLBAS-Project/LOLBAS/pull/239
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_installutil_download.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2022-08-19
modified: 2023-11-09
tags:
  - attack.stealth
  - attack.t1218
logsource:
  category: process_creation
  product: windows
detection:
  selection_img:
    - Image|endswith: \InstallUtil.exe
    - OriginalFileName: InstallUtil.exe
  selection_cli:
    CommandLine|contains:
      - ftp://
      - http://
      - https://
  condition: all of selection_*
falsepositives:
  - Unknown
level: medium
license: DRL-1.1
related:
  - id: 75edd216-1939-4c73-8d61-7f3a0d85b5cc
    type: derived

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