__Notice

I really wonder why the Mozilla Foundation decided to release a serious
security update on a friday night and to disclose the link to my
proof-of-concept code so quickly. It wasn't intendet from my side to release
this as a 0day exploit. Please complain to security@mozilla.org if you
disagree with their release policy.

__Summary

The link tag allows to load a custom image as the icon for a website,
displayed in the location bar and in the tab title.

By setting the href attribute of this tag to a javascript url, it is
possible to call chrome functions and run arbitrary code without user
interaction.

__Proof-of-Concept

http://www.mikx.de/firelinking/

__Status

The bug is fixed in Firefox 1.0.3. Disable javascript as a workaround.

2005-04-12 Vendor informed (bugzilla.mozilla.org #290036)
2005-04-12 Vendor confirmed bug
2005-04-15 Vendor published fix, advisory and link to PoC (mfsa2005-37)
2005-04-18 This advisory

__Affected Software

Tested with Firefox 1.0.2

__Contact Informations

Michael Krax <mikx@mikx.de>
http://www.mikx.de/?p=15

mikx