title: Powershell AMSI Bypass via .NET Reflection
author: Markus Neis
date: 2018/08/17
description: Detects Request to amsiInitFailed that can be used to disable AMSI Scanning
detection:
  SELECTION_1:
    EventID: 1
  SELECTION_2:
    CommandLine:
    - '*System.Management.Automation.AmsiUtils*'
  SELECTION_3:
    CommandLine:
    - '*amsiInitFailed*'
  condition: (SELECTION_1 and SELECTION_2 and SELECTION_3)
falsepositives:
- Potential Admin Activity
id: 30edb182-aa75-42c0-b0a9-e998bb29067c
level: high
logsource:
  category: process_creation
  product: windows
modified: 2020/09/01
references:
- https://twitter.com/mattifestation/status/735261176745988096
- https://www.hybrid-analysis.com/sample/0ced17419e01663a0cd836c9c2eb925e3031ffb5b18ccf35f4dea5d586d0203e?environmentId=120
status: experimental
tags:
- attack.defense_evasion
- attack.t1089
- attack.t1562.001
ruletype: SIGMA