nim shellcode testing

import winim, strutils

var
  someCode: array[0x10, uint8]
  codeAddr: pointer = addr(someCode)

# some dummy testing code for PoC purposes
someCode[0] = 0x90 # NOP
someCode[1] = 0x90 # NOP
someCode[2] = 0x90 # NOP
someCode[3] = 0xc3 # RETN

# note: repr(ptr) will show the addr and reference
echo "placed code at address 0x" & cast[int](codeAddr).toHex

# allocate memory
# https://msdn.microsoft.com/en-us/library/windows/desktop/aa366887(v=vs.85).aspx
#
# VirtualAlloc(
#   _In_opt_ LPVOID lpAddress,
#   _In_     SIZE_T dwSize,
#   _In_     DWORD  flAllocationType,
#   _In_     DWORD  flProtect);
#
# winim:
# proc VirtualAlloc*(P1: PVOID, P2: DWORD, P3: DWORD, P4: DWORD): PVOID
# {.winapi, dynlib: "kernel32", importc.}

var lpvAddr: LPVOID

lpvAddr = VirtualAlloc(nil, DWORD(sizeof(someCode)), MEM_COMMIT, PAGE_READWRITE)
echo "VirtualAlloc returned 0x" & cast[int](lpvAddr).toHex

# copy code to allocated memory
copyMem(lpvAddr, codeAddr, sizeof(someCode))

# create a thread
# https://msdn.microsoft.com/en-us/library/windows/desktop/ms682453(v=vs.85).aspx
#
# CreateThread(
#  _In_opt_  LPSECURITY_ATTRIBUTES  lpThreadAttributes,
#  _In_      SIZE_T                 dwStackSize,
#  _In_      LPTHREAD_START_ROUTINE lpStartAddress,
#  _In_opt_  LPVOID                 lpParameter,
#  _In_      DWORD                  dwCreationFlags,
#  _Out_opt_ LPDWORD                lpThreadId);
#
# winim:
# proc CreateThread*(P1: LPSECURITY_ATTRIBUTES, P2: DWORD, P3: LPTHREAD_START_ROUTINE,
# P4: PVOID, P5: DWORD, P6: PDWORD): HANDLE {.winapi, dynlib: "kernel32", importc.}

var
  dummyThreadId: PDWORD
  thread: HANDLE

thread = CreateThread(nil, DWORD(0), lpvAddr, nil, DWORD(0), dummyThreadId)

# COMPILE/RUN RESULT:
# win_test.nim(55, 22) Error: type mismatch: got (nil, DWORD, LPVOID, nil, DWORD, PDWORD)
# but expected one of:
# proc CreateThread(self: DEBUG_EVENT): CREATE_THREAD_DEBUG_INFO
# proc CreateThread(P1: LPSECURITY_ATTRIBUTES; P2: DWORD; P3: LPTHREAD_START_ROUTINE;
#                P4: PVOID; P5: DWORD; P6: PDWORD): HANDLE