AMSI Disabled via Registry Modification

Hunt Hypothesis

Detects attempts to disable AMSI (Anti-Malware Scan Interface) by modifying the AmsiEnable registry value. Anti-Malware Scan Interface (AMSI) is a security feature in Windows that allows applications

Detection Rule

Sigma (Original)

title: AMSI Disabled via Registry Modification
id: aa37cbb0-da36-42cb-a90f-fdf216fc7467
related:
    - id: 7dbbcac2-57a0-45ac-b306-ff30a8bd2981 # Windows AMSI Related Registry Tampering Via CommandLine
      type: similar
status: experimental
description: |
    Detects attempts to disable AMSI (Anti-Malware Scan Interface) by modifying the AmsiEnable registry value.
    Anti-Malware Scan Interface (AMSI) is a security feature in Windows that allows applications and services to integrate with anti-malware products for enhanced protection against malicious content.
    Adversaries may attempt to disable AMSI to evade detection by security software, allowing them to execute malicious scripts or code without being scanned.
references:
    - https://mostafayahiax.medium.com/hunting-for-amsi-bypassing-methods-9886dda0bf9d
    - https://docs.microsoft.com/en-us/windows/win32/amsi/antimalware-scan-interface-portal
    - 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-evasion
    - attack.t1562.001
    - attack.t1562.006
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|endswith: '\Software\Microsoft\Windows Script\Settings\AmsiEnable'
        Details: 'DWORD (0x00000000)'
    condition: selection
falsepositives:
    - Unlikely
level: high
regression_tests_path: regression_data/rules/windows/registry/registry_set/registry_set_amsi_disable/info.yml
simulation:
    - type: atomic-red-team
      name: AMSI Bypass - Create AMSIEnable Reg Key
      technique: T1562.001
      atomic_guid: 728eca7b-0444-4f6f-ac36-437e3d751dc0

KQL (Azure Sentinel)

imRegistry
| where RegistryKey endswith "\\Software\\Microsoft\\Windows Script\\Settings\\AmsiEnable" and RegistryValueData =~ "DWORD (0x00000000)"

KQL (Microsoft 365 Defender)

DeviceRegistryEvents
| where RegistryKey endswith "\\Software\\Microsoft\\Windows Script\\Settings\\AmsiEnable" and RegistryValueData =~ "DWORD (0x00000000)"

Required Data Sources

False Positive Guidance

• Unlikely

MITRE ATT&CK Context

• Tactic: Defense Evasion
• Technique: T1562.001 — T1562.001
• Technique: T1562.006 — T1562.006

References

• https://mostafayahiax.medium.com/hunting-for-amsi-bypassing-methods-9886dda0bf9d
• https://docs.microsoft.com/en-us/windows/win32/amsi/antimalware-scan-interface-portal
• https://www.mdsec.co.uk/2019/02/macros-and-more-with-sharpshooter-v2-0/
• SigmaHQ Rule