MSIE 5 favicon bug

[flaviovs () CENTROIN COM BR (Flavio Veloso)]

Hi folks.

When MSIE 5 users bookmark a page, the browser will request a file
named "favicon.ico" which is to be used in the "Favorites" menu of the
browser. Unfortunately MSIE 5 doesn't check the file integrity and
crash if faced with a bad-formed icon file.

Upon crashing the stack gets filled with information from the icon
file itself, so it may be possible to run code on the client machine,
tough I didn't test it.

Microsoft was notified twice about this issue via the "Report a Bug"
form on their web site. The first time about one month ago, the second
time about two weeks ago. I didn't receive back any reply.

More information about this bug (plus another privacy issue about the
"favicon.ico" file) is available at
http://web.cip.com.br/flaviovs/sec/favicon/index.html.

--
Flavio