PowerShell Reflection-Based AMSI Bypass via amsiInitFailed Field Manipulation
Detects the use of .NET reflection within PowerShell scripts to manipulate the 'amsiInitFailed' field in 'System.Management.Automation.AmsiUtils'. This technique is a common method to disable the Antimalware Scan Interface (AMSI) for the current process session. The rule monitors PowerShell script block logs for the co-occurrence of AMSI-related classes/fields and specific reflection primitives.
Microsoft Sentinel (KQL)
