Emmanouel Kellinis has reported a vulnerability in Mozilla and Mozilla Firefox, allowing malicious sites to abuse SSL certificates of other sites.

It is possible to make the browser load a valid certificate from a trusted website by using a specially crafted "onunload" event. The problem is that Mozilla loads the certificate from a trusted website and shows the "secure padlock" while actually displaying the content of the malicious website.

The URL shown in the address bar correctly reads that of the malicious website.

This has been confirmed using Mozilla Firefox 0.9.2 and Mozilla 1.7.1 on Windows and Mozilla Firefox 0.9.1 on Linux. Other versions may also be affected.

Solution
The vulnerability has been fixed in the following versions:
Further details available to Secunia VIM customers

Provided and/or discovered by
Emmanouel Kellinis

Changelog
Further details available to Secunia VIM customers

Original Advisory
Emmanouel Kellinis:
http://www.cipher.org.uk/index.php?p=advisories/Certificate_Spoofing_Mozilla_FireFox_25-07-2004.advisory

Mozilla Bug Tracking System:
http://bugzilla.mozilla.org/show_bug.cgi?id=253121

Deep Links
Links available to Secunia VIM customers