Windows AMSI Related Registry Tampering Via CommandLine — Sigma Rule

Rule metadata and linked tags

Author: Swachchhanda Shrawan Poudel (Nextron Systems). Source status: experimental; severity: high. Source dates: 2025-12-25 / not supplied.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 8d4365ec898b73410a31b06d24f6395dabf916d723f09ae5442c47e9c7b4ec98

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Windows AMSI Related Registry Tampering Via CommandLine
id: 7dbbcac2-57a0-45ac-b306-ff30a8bd2981
related:
    - id: aa37cbb0-da36-42cb-a90f-fdf216fc7467 # AMSI Disabled via Registry Modification
      type: similar
status: experimental
description: |
    Detects tampering of AMSI (Anti-Malware Scan Interface) related registry values via command line tools such as reg.exe or PowerShell.
    AMSI provides a generic interface for applications and services to integrate with antimalware products.
    Adversaries may disable AMSI to evade detection of malicious scripts and code execution.
references:
    - https://github.com/arttoolkit/arttoolkit.github.io/blob/16d6230d009e58fd6f773f5317fd4d14c1f26004/_wadcoms/AMSI-Bypass-Jscript_amsienable.md
    - https://mostafayahiax.medium.com/hunting-for-amsi-bypassing-methods-9886dda0bf9d
    - https://www.mdsec.co.uk/2019/02/macros-and-more-with-sharpshooter-v2-0/
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-12-25
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    category: process_creation
    product: windows
detection:
    selection_key:
        CommandLine|contains|all:
            - '\Software\Microsoft\Windows Script\Settings'
            - 'AmsiEnable'
    selection_reg_img:
        - Image|endswith: '\reg.exe'
        - OriginalFileName: 'reg.exe'
    selection_reg_cmd:
        CommandLine|contains: 'add'
    selection_powershell_img:
        - Image|endswith:
              - '\powershell.exe'
              - '\pwsh.exe'
        - OriginalFileName:
              - 'PowerShell.EXE'
              - 'pwsh.dll'
    selection_powershell_cmd:
        CommandLine|contains:
            - 'Set-ItemProperty'
            - 'New-ItemProperty'
            - 'sp '
    condition: selection_key and (all of selection_powershell_* or all of selection_reg_*)
falsepositives:
    - Unknown
level: high
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_amsi_registry_tampering/info.yml
simulation:
    - type: atomic-red-team
      name: AMSI Bypass - Create AMSIEnable Reg Key
      technique: T1562.001
      atomic_guid: 728eca7b-0444-4f6f-ac36-437e3d751dc0

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://github.com/arttoolkit/arttoolkit.github.io/blob/16d6230d009e58fd6f773f5317fd4d14c1f26004/_wadcoms/AMSI-Bypass-Jscript_amsienable.md
• https://mostafayahiax.medium.com/hunting-for-amsi-bypassing-methods-9886dda0bf9d
• https://www.mdsec.co.uk/2019/02/macros-and-more-with-sharpshooter-v2-0/