Firefox cross-domain text theft (CESA-2008-011) Dec 18 2008 09:00AM
Chris Evans (scarybeasts gmail com)
Hi,

Firefoxes 2.0.0.19 and 3.0.5 fix a cross-domain theft of textual data.
The theft is via cross-domain information leaks in JavaScript error
messages for scripts executed via <script src="remote_domain.org">.
The JavaScript error messages are made available to the window.onerror
handler. In some cases, JavaScript error messages can contain pieces
of text from the remote domain as part of the error message, e.g.
"blah is not defined". This permits certain textual constructs to be
stolen cross-domain.

The broader issue was fixed in Firefox 3.0. However this fix was not
complete. The fix could be dodged by using another instance of the
"302 redirect trick". It was possible to cause the browser to believe
a remote script was in fact local, and therefore continue to reveal
JavaScript error messages.

Advisory: http://scary.beasts.org/security/CESA-2008-011.html

Blog post: http://scarybeastsecurity.blogspot.com/2008/12/firefox-cross-domain-text
-theft.html

Cheers
Chris

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