Windows: Detect Loading amsi.dll by LOLBIN Processes

Alert on amsi.dll DLL loads initiated by ExtExport.exe, Odbcconf.exe, or Rundll32.exe on Windows.

FreeReviewedSigma · Medium · v2
Product
windows
Category
image_load
Author
Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2023-06-01
Updated
2026-07-31
title: "Windows: Detect Loading amsi.dll by LOLBIN Processes"
id: 446af65d-8952-4c67-972b-92481ec46bd3
status: test
description: This rule flags events where a process loads amsi.dll via common living-off-the-land executables (ExtExport.exe, odbcconf.exe, or rundll32.exe). Loading amsi.dll outside expected application flows can indicate defense-impairment behavior where attackers interact with Windows security interfaces. It relies on Windows image load telemetry indicating which module was loaded and which process performed the load.
references:
  - Internal Research
  - https://www.paloaltonetworks.com/blog/security-operations/stopping-powershell-without-powershell/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/image_load/image_load_dll_amsi_suspicious_process.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2023-06-01
modified: 2025-10-07
tags:
  - attack.defense-impairment
logsource:
  category: image_load
  product: windows
detection:
  selection:
    ImageLoaded|endswith: \amsi.dll
    Image|endswith:
      - \ExtExport.exe
      - \odbcconf.exe
      - \rundll32.exe
  condition: selection
falsepositives:
  - Unknown
level: medium
license: DRL-1.1
related:
  - id: 6ec86d9e-912e-4726-91a2-209359b999b9
    type: derived