Suspicious DllUnregisterServer Function Call Through Msiexec.EXE (via process_creation)

title: Suspicious DllUnregisterServer Function Call Through Msiexec.EXE (via process_creation)
id: 38d44120-768f-57dd-8450-4c983cbe8382
status: stable
description: This rule detects MsiExec loading a DLL and calling its DllUnregisterServer function
references:
    - https://attack.mitre.org/techniques/T1218/007/
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1218.007/T1218.007.md
    - https://lolbas-project.github.io/lolbas/Binaries/Msiexec/
    - https://twitter.com/_st0pp3r_/status/1583914515996897281
author: Huntrule Team
date: 2026-06-27
tags:
    - attack.stealth
    - attack.t1218.007
logsource:
    product: windows
    category: process_creation
detection:
    selection_img:
        - Image|endswith: '\msiexec.exe'
        - OriginalFileName: '\msiexec.exe'
    selection_flag:
        CommandLine|contains|windash: ' -z '
    selection_dll:
        CommandLine|contains: '.dll'
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium