Execution of Unusual AddinUtil.EXE CommandLine (via process_creation)

title: Execution of Unusual AddinUtil.EXE CommandLine (via process_creation)
id: 9432ee38-6fb2-51d4-8f86-330ef472714a
status: stable
description: This rule detects execution of the Add-In deployment cache updating utility (AddInutil.exe) with uncommon Addinroot or Pipelineroot paths. An adversary may execute AddinUtil.exe with uncommon Addinroot/Pipelineroot paths that point to the threat actors Addins.Store payload.
references:
    - https://attack.mitre.org/techniques/T1218/
    - https://www.blue-prints.blog/content/blog/posts/lolbin/addinutil-lolbas.html
author: Huntrule Team
date: 2026-04-20
tags:
    - attack.stealth
    - attack.t1218
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\addinutil.exe'
        - OriginalFileName: 'AddInUtil.exe'
    selection_cli:
        CommandLine|contains:
            - '-AddInRoot:'
            - '-PipelineRoot:'
    filter_main_addinroot:
        CommandLine|contains:
            - '-AddInRoot:"C:\Program Files (x86)\Common Files\Microsoft Shared\VSTA'
            - '-AddInRoot:C:\Program Files (x86)\Common Files\Microsoft Shared\VSTA'
            - '-PipelineRoot:"C:\Program Files (x86)\Common Files\Microsoft Shared\VSTA'
            - '-PipelineRoot:C:\Program Files (x86)\Common Files\Microsoft Shared\VSTA'
    condition: all of selection_* and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium