Possible Persistence Through New AMSI Providers - Registry (via registry_set)

title: Possible Persistence Through New AMSI Providers - Registry (via registry_set)
id: 43d2f6bc-f768-5a46-965a-43a27e27707b
status: stable
description: This rule detects when an adversary adds a new AMSI provider via the Windows Registry to bypass AMSI (Antimalware Scan Interface) protections. Attackers may add custom AMSI providers to persist on the system and evade detection by security software that relies on AMSI for scanning scripts and other content. This method is frequently used in conjunction with fileless malware and script-based attacks to maintain persistence while avoiding detection.
references:
    - https://persistence-info.github.io/Data/amsi.html
    - https://github.com/gtworek/PSBits/blob/8d767892f3b17eefa4d0668f5d2df78e844f01d8/FakeAMSI/FakeAMSI.c
author: Huntrule Team
date: 2026-03-22
tags:
    - attack.persistence
    - attack.defense-evasion
    - attack.t1546
    - attack.t1562.001
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|contains:
            - '\SOFTWARE\Microsoft\AMSI\Providers\'
            - '\SOFTWARE\WOW6432Node\Microsoft\AMSI\Providers\'
    filter_optional_avast:
        Image:
            - 'C:\Program Files\Avast Software\Avast\RegSvr.exe'
            - 'C:\Program Files\Avast Software\Avast\x86\RegSvr.exe'
        TargetObject|contains: '\{FB904E4E-D2C7-4C8D-8492-B620BB9896B1}'
    filter_optional_avg:
        Image:
            - 'C:\Program Files\AVG\Antivirus\RegSvr.exe'
            - 'C:\Program Files\AVG\Antivirus\x86\RegSvr.exe'
        TargetObject|contains: '\{FB904E4E-D2C7-4C8D-8492-B620BB9896B1}'
    filter_optional_avira:
        Image: 'C:\Program Files\Avira\Endpoint Protection SDK\endpointprotection.exe'
        TargetObject|contains: '\{00000001-3DCC-4B48-A82E-E2071FE58E05}'
    condition: selection and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium
regression_tests_path: regression_data/rules/windows/registry/registry_set/registry_set_persistence_amsi_providers/info.yml