Windows AMSI Provider Registry Key Deletion (HKLM\Software\Microsoft\AMSI)

ATT&CK techniques

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags deletion of specific AMSI provider registry key entries under HKLM\Software\Microsoft\AMSI. Removing these entries can be used by an attacker to impair or disable AMSI-based inspection. The detection relies on Windows registry delete telemetry for the matching TargetObject identifiers, with exclusions for common Windows Defender platform activity associated with MsMpEng.exe.

Reporting behind it

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Windows AMSI Provider Registry Key Deletion (HKLM\Software\Microsoft\AMSI)

Pivot detection · T1685 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-amsi-provider-registry-key-deletion-hklm-software-microsoft-amsi-41d1058a

title: Windows AMSI Provider Registry Key Deletion (HKLM\Software\Microsoft\AMSI)
id: b5db911d-3827-4793-8d95-35a4af0c4f2e
status: test
description: This rule flags deletion of specific AMSI provider registry key entries under HKLM\Software\Microsoft\AMSI. Removing these entries can be used by an attacker to impair or disable AMSI-based inspection. The detection relies on Windows registry delete telemetry for the matching TargetObject identifiers, with exclusions for common Windows Defender platform activity associated with MsMpEng.exe.
references:
  - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.001/T1562.001.md
  - https://seclists.org/fulldisclosure/2020/Mar/45
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/registry/registry_delete/registry_delete_removal_amsi_registry_key.yml
author: frack113, Huntrule Team
date: 2021-06-07
modified: 2025-10-07
tags:
  - attack.defense-impairment
  - attack.t1685
logsource:
  product: windows
  category: registry_delete
detection:
  selection:
    TargetObject|endswith:
      - "{2781761E-28E0-4109-99FE-B9D127C57AFE}"
      - "{A7C452EF-8E9F-42EB-9F2B-245613CA0DC9}"
  filter_main_defender:
    Image|startswith:
      - C:\ProgramData\Microsoft\Windows Defender\Platform\
      - C:\Program Files\Windows Defender\
      - C:\Program Files (x86)\Windows Defender\
    Image|endswith: \MsMpEng.exe
  condition: selection and not 1 of filter_main_*
falsepositives:
  - Unlikely
level: high
regression_tests_path: regression_data/rules/windows/registry/registry_delete/registry_delete_removal_amsi_registry_key/info.yml
simulation:
  - type: atomic-red-team
    name: AMSI Bypass - Remove AMSI Provider Reg Key
    technique: T1562.001
    atomic_guid: 13f09b91-c953-438e-845b-b585e51cac9b
license: DRL-1.1
related:
  - id: 41d1058a-aea7-4952-9293-29eaaf516465
    type: derived

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