Jsc.exe

type: OSBinaries

Binary file used by .NET to compile JavaScript code to .exe or .dll format

Full path

C:\Windows\Microsoft.NET\Framework\v4.0.30319\Jsc.exe
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Jsc.exe
C:\Windows\Microsoft.NET\Framework\v2.0.50727\Jsc.exe
C:\Windows\Microsoft.NET\Framework64\v2.0.50727\Jsc.exe

Commands

CompileUser T1127
Compile attacker code on system. Bypass defensive counter measures.
```
jsc.exe {PATH:.js}
```
Use jsc.exe to compile JavaScript code stored in the provided .JS file and generate a .EXE file with the same name.
os: Windows vista, Windows 7, Windows 8, Windows 8.1, Windows 10, Windows 11
Execute: JScript
CompileUser T1127
Compile attacker code on system. Bypass defensive counter measures.
```
jsc.exe /t:library {PATH:.js}
```
Use jsc.exe to compile JavaScript code stored in the .JS file and generate a DLL file with the same name.
os: Windows vista, Windows 7, Windows 8, Windows 8.1, Windows 10, Windows 11
Execute: JScript

Detection

Sigma https://github.com/SigmaHQ/sigma/blob/35a7244c62820fbc5a832e50b1e224ac3a1935da/rules/windows/process_creation/proc_creation_win_lolbin_jsc.yml
IOCJsc.exe should normally not run a system unless it is used for development.

Resources

acknowledgement: Malwrologist @DissectMalware