Sigma rule: Amsi.DLL Loaded Via LOLBIN Process

Rule

Title

Amsi.DLL Loaded Via LOLBIN Process

Status

test

Level

medium

Author

Nasreddine Bencherchali (Nextron Systems)

Date

2023-06-01

Modified

2025-10-07

File

rules/windows/image_load/image_load_dll_amsi_suspicious_process.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects loading of "Amsi.dll" by a living of the land process. This could be an indication of a "PowerShell without PowerShell" attack

Log source

product

windows

category

image_load

Detection

selection:
    ImageLoaded|endswith: '\amsi.dll'
    Image|endswith:
        # TODO: Add more interesting processes
        - '\ExtExport.exe'
        - '\odbcconf.exe'
        # - '\regsvr32.exe' # legitimately calls amsi.dll
        - '\rundll32.exe'
condition: selection

False positives (as the rule lists them)

• Unknown

Tags

• attack.defense-impairment

References

• Internal Research
• https://www.paloaltonetworks.com/blog/security-operations/stopping-powershell-without-powershell/

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/image_load/image_load_dll_amsi_suspicious_process.yml