Re: More reading of local files in MSIE

From: Dave Ahmad (daat_private)
Date: Fri Jan 04 2002 - 16:47:52 PST

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    Jelmer,
    
    Exploitation is not limited to disclosing the contents of files on client
    systems.  If your exploit page is modified so that a website is opened rather
    than a local file, the calling script can access the properties of the
    website.  The problem here is that IE6/5.5 does not properly enforce
    the same origin policy.
    
    I believe that this is just another way to exploit the same basic
    (but extremely serious) problem that was reported by The Pull in this
    post:
    
    http://www.securityfocus.com/archive/1/246522
    
    Also see this entry in the SecurityFocus Vulnerability Database:
    
    http://www.securityfocus.com/bid/3721
    
    I have not yet seen a public response from Microsoft.  According to The
    Pull, they were notified (it also went over the list).
    
    Dave Ahmad
    SecurityFocus
    www.securityfocus.com
    
    On Fri, 4 Jan 2002, jelmer wrote:
    
    > More reading of local files in MSIE
    >
    > Description
    >
    >
    > There is a security vulnerability in IE 5.5 and 6 (probably other
    > versions as well) which allows reading and sending of local files.
    > The problem lies in the fact that you are able to access a local file's
    > dom by calling the execScript function on a newly created window
    > The sample exploit provided can only read browser readable files however
    > it is highly likely that reading binary files is possible as well
    > (By attaching an event to the dom that calls the httpxmlcomponent, witch
    > itself at the point of writing is still vulnerable as well)
    > In order for this exploit to work the file name must be known.
    >
    > Risk
    >
    > High
    >
    > Systems affected:
    >
    > The vulnerability has been successfully exploited on
    > IE 6 / Windows XP with all patches installed
    > IE 5.5 / Windows ME
    



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