Windows network connections initiated by AddinUtil.exe

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 network connections where Initiated is true and the initiating process image ends with Addinutil.exe. Addinutil.exe is not expected to normally start outbound network communication, so unexpected activity may indicate attacker abuse for command-and-control. It relies on Windows network connection telemetry that includes the initiating process identifier and image path.

Reporting behind it

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Windows network connections initiated by AddinUtil.exe

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-addinutil-exe-initiates-network-connection-5205613d

title: Windows network connections initiated by AddinUtil.exe
id: 7171883e-5169-4dfd-83f1-3de03e3180ad
status: test
description: This rule flags network connections where Initiated is true and the initiating process image ends with Addinutil.exe. Addinutil.exe is not expected to normally start outbound network communication, so unexpected activity may indicate attacker abuse for command-and-control. It relies on Windows network connection telemetry that includes the initiating process identifier and image path.
references:
  - https://www.blue-prints.blog/content/blog/posts/lolbin/addinutil-lolbas.html
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/network_connection/net_connection_win_addinutil_initiated.yml
author: Michael McKinley (@McKinleyMike), Tony Latteri (@TheLatteri), Huntrule Team
date: 2023-09-18
modified: 2024-07-16
tags:
  - attack.stealth
  - attack.t1218
logsource:
  category: network_connection
  product: windows
detection:
  selection:
    Initiated: "true"
    Image|endswith: \addinutil.exe
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 5205613d-2a63-4412-a895-3a2458b587b3
    type: derived

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