MSIE Overly Trusted Location Variant Method Cache Vulnerability

From: Paul (paul_at_greyhats.cjb.net)
Date: 07/17/04

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    Date: 17 Jul 2004 03:06:57 -0000
To: bugtraq@securityfocus.com
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    This vulnerability as well as many more can be found at http://www.greyhats.cjb.net

    Overly Trusted Location Variant Method Cache Vulnerability

    [Tested]
    IEXPLORE.EXE file version 6.0.2800.1106
    MSHTML.DLL file version 6.00.2800.1400
    Microsoft Windows XP sp1

    [Discussion]
    Apparently, Internet Explorer trusts the location variant way too much when it comes to method cache. As Thor Larholm pointed out to me, it isnt a problem of similar method name redirection, but a problem with the location variant. I have created a new vulnerability to demonstrate this. EvilChild creates a child popup on a new window. Then it redirects the page. As it's loading, the popup is shown and saves the ref of parent.window.open to location.cache. As soon as the evil child popup cannot access the parent.document, an error handler is fired calling parent.window.open to load javascript into the main window.

    Example can be found at http://freehost07.websamba.com/greyhats/evilchild.htm

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