32/64-bit FSharp (F#) Interpreter included with Visual Studio.
fsianycpu.exe c:\path\to\test.fsscript
Execute F# code via script file
Execute payload with Microsoft signed binary to bypass WDAC policies
c:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\Common7\IDE\CommonExtensions\Microsoft\FSharp\fsianycpu.exe
BlockRule: https://docs.microsoft.com/en-us/windows/security/threat-protection/windows-defender-application-control/microsoft-recommended-block-rules, IOC: FsiAnyCpu.exe execution may be suspicious on non-developer machines, Sigma: https://github.com/SigmaHQ/sigma/blob/6b34764215b0e97e32cbc4c6325fc933d2695c3a/rules/windows/process_creation/proc_creation_win_lolbin_fsharp_interpreters.yml
Nick Tyrer (@NickTyrer), Jimmy (@bohops)