.. /Jsc.exe
Star

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

Paths:

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

Resources:

Acknowledgements:

Malwrologist (@DissectMalware)

Detection:

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

Compile

Use jsc.exe to compile JavaScript code stored in scriptfile.js and output scriptfile.exe.
```
jsc.exe scriptfile.js
```
Use case
Compile attacker code on system. Bypass defensive counter measures.

Privileges required
User

Operating systems
Windows vista, Windows 7, Windows 8, Windows 8.1, Windows 10, Windows 11

ATT&CK® technique
T1127

Tags
Execute: WSH
This LOLBAS executes scripts in Windows Script Host (WSH) languages, such as VBScript and JScript.
Use jsc.exe to compile JavaScript code stored in Library.js and output Library.dll.
```
jsc.exe /t:library Library.js
```
Use case
Compile attacker code on system. Bypass defensive counter measures.

Privileges required
User

Operating systems
Windows vista, Windows 7, Windows 8, Windows 8.1, Windows 10, Windows 11

ATT&CK® technique
T1127

Tags
Execute: WSH
This LOLBAS executes scripts in Windows Script Host (WSH) languages, such as VBScript and JScript.