Encontre este directorio:

external/source/shellcode/windows/x86

En la carpeta del MSF.

Me imagino que es obvia la respuesta, pero por si acaso me ahorro un poco de tiempo preguntando... ¿Entonces aqui es en donde esta el source? xdddddd

This directory contains the win32 payload development environment used
for creating the payloads in version 3 of the Metasploit Framework.

The 'nasm' executable must be in your path to use the included build.sh tool.

The included 'build' script automatically creates a number of file types
each time it used to compile a payload. These file types are:

    - Native ELF executable
    - Win32 PE executable
    - Generated C source code
    - Raw opcodes in ".bin" format

The PE executable templates were developed by 'rix' and used with permission.

To use this script, simply run ./build.sh <name of payload>, where the name
does not include the ".asm" suffix. To build win32_stage_api.asm, the
command line would be "./build.sh win32_stage_api".

me podrias decir como? porfavor...