Mozilla Firefox Certificate Spoofing

28.07.2004 09:32:59

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Application: Mozilla Firefox
Vendors: www.mozilla.com...
Version: 0.9.1 / 0.9.2
Platforms: Windows
Bug: Certificate Spoofing (Phishing)
Risk: High
Exploitation: Remote with browser
Date: 25 July 2004
Author: Emmanouel Kellinis
e-mail: me@cipher(dot)org(dot)uk
web: www.cipher.org.uk...
List : BugTraq(SecurityFocus)/ Full-Disclosure
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=======
Product
=======
A popular Web browser,good alternative of IE and
"The web browser" for linux machines,
used to view pages on the World Wide Web.

===
Bug
===

Firefox has caching problem, as a result of that someone can
spoof a certificate of any website and use it as his/her own.
The problem is exploited using onunload inside < body> and
redirection using Http-equiv Refresh metatag,document.write()
and document.close()

First you direct the redirection metatag to the website
of which you want to spoof the certificate, then inside
the < body> tag you add onulnoad script so you can control
the output inside the webpage with the spoofed certificate.

After that you say to firefox, as soon as you unload this page
close the stream, aparently the stream you close is
the redirection website, you do that with
document.close().

Now you can write anything you want , you do that
using document.write(). After writing the content of you choice
you close the stream again , usually firefox wont display your content,
although if you check the source code you see it , so the last thing
is to refresh the new page (do that using window.location.reload()),
after that you have your domain name in the url field , your content
in the browser and the magic yellow Lock on the bottom left corner,
if you pass your mouse over it you will see displayed the name of
the website you spoofed the certificate, if you double click on it you
will check full information of the certificate without any warning !

You dont need to have SSL in your website ! it will work with
http.

Additional using this bug malicious websites can bypass content
filtering using SSL properties.


=====================
Proof Of Concept Code
=====================

< HTML>
< HEAD>
< TITLE>Spoofer< /TITLE>
< META HTTP-EQUIV="REFRESH" CONTENT="0;URL=https://www.example.com">
< /HEAD>
< BODY
onunload="
document.close();
document.writeln('< body onload=document.close();break;>
< h3>It is Great to Use example's Cert!');

document.close();
window.location.reload();
">
< /body>


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*PK:www.cipher.org.uk...
=========================================================

Zoiks! Thanks for the heads-up.

Now to decide which is riskier for online banking: Mozilla or IE.

I wonder if this will effect knoqueror(gecko rendering engine)