Detectionhightest

Potential AMSI Bypass Via .NET Reflection

Detects Request to "amsiInitFailed" that can be used to disable AMSI Scanning

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Markus NeisCreated Fri Aug 17Updated Fri Feb 0330edb182-aa75-42c0-b0a9-e998bb29067cwindows

Log Source

WindowsProcess Creation

ProductWindows← raw: windows

CategoryProcess Creation← raw: process_creation

Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.

Detection Logic

detection:
    selection:
        - CommandLine|contains|all:
              - 'System.Management.Automation.AmsiUtils'
              - 'amsiInitFailed'
        - CommandLine|contains|all:
              - '[Ref].Assembly.GetType'
              - 'SetValue($null,$true)'
              - 'NonPublic,Static'
    condition: selection