Windows: Uncommon Child Processes Spawned by Addinutil.exe

Alerts when Addinutil.exe launches an uncommon child process, indicating potential proxy execution abuse.

FreeReviewedSigma · Medium · v2

Product: windows
Category: process_creation
Author: Michael McKinley (@McKinleyMike), Tony Latteri (@TheLatteri) (SigmaHQ), DRL 1.1
Published: 2023-09-18
Updated: 2026-07-31

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 flags process creation events where the parent process is Addinutil.exe and the resulting child process is uncommon. Attackers may abuse Addinutil.exe as a proxy execution mechanism using a custom Addins.Store payload, so unexpected child processes can indicate stealthy execution. The detection relies on Windows process creation telemetry and matches parent-child relationships using process image path suffixes, while excluding common error reporting processes (conhost.exe and werfault.exe variants).

Reporting behind it

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Windows: Uncommon Child Processes Spawned by Addinutil.exe

Pivot detection · T1218 · 9 related

Changelog

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-uncommon-child-processes-spawned-by-addinutil-exe-b5746143

title: "Windows: Uncommon Child Processes Spawned by Addinutil.exe"
id: 515c7b91-323d-427a-b6de-5e5a33d3ab1e
status: test
description: This rule flags process creation events where the parent process is Addinutil.exe and the resulting child process is uncommon. Attackers may abuse Addinutil.exe as a proxy execution mechanism using a custom Addins.Store payload, so unexpected child processes can indicate stealthy execution. The detection relies on Windows process creation telemetry and matches parent-child relationships using process image path suffixes, while excluding common error reporting processes (conhost.exe and werfault.exe variants).
references:
  - https://www.blue-prints.blog/content/blog/posts/lolbin/addinutil-lolbas.html
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_addinutil_uncommon_child_process.yml
author: Michael McKinley (@McKinleyMike), Tony Latteri (@TheLatteri), Huntrule Team
date: 2023-09-18
tags:
  - attack.stealth
  - attack.t1218
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    ParentImage|endswith: \addinutil.exe
  filter_main_werfault:
    Image|endswith:
      - :\Windows\System32\conhost.exe
      - :\Windows\System32\werfault.exe
      - :\Windows\SysWOW64\werfault.exe
  condition: selection and not 1 of filter_main_*
falsepositives:
  - Unknown
level: medium
license: DRL-1.1
related:
  - id: b5746143-59d6-4603-8d06-acbd60e166ee
    type: derived

Convert

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