MSIE vulnerability exploitable with Eudora (was: IncrediMail)

From: Magnus Bodin (magnusat_private)
Date: Sat Mar 16 2002 - 08:23:16 PST

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    On Fri, Mar 15, 2002 at 06:33:21PM +0100, Eric Detoisien wrote:
    > Hi,
    > 
    > 	A Microsoft Internet Explorer vulnerability was found by GreyMagic
    > (http://security.greymagic.com/adv/gm001-ie/). With IncrediMail, it's
    > possible to gain a remote access on a computer.
    > 
    > 	Incredimail save automatically email attachements in this directory 
    > (on Windows 2000 Professionnal) :
    > C:\Program Files\IncrediMail\Data\Identities\{42D00B20-479C-11d4-9706-00105A40931C}\Message Store\Attachments
    
    
    Affects: Most (All?) Eudora-versions on MS/Windows.
    
    This would make most versions of Eudora equally vulnerable.
    Eudora (all versions I know of) automatically decodes attachments and stores them in the attachment
    directory of Eudora. (This may vary between versions and platform, but is
    pretty much easy to guess and with this greymagic-exploit-test:
    
    	<http://x42.com/test/calc.jpg>
    
    (Fires off the windows calculator, but could easily be modified to exploit
    an auto-decoded attachment instead)
    
    To exploit this one could send the attachment in an e-mail and include a
    link to a page which servers such an exploiting image/etc. _OR_ if Eudora
    uses embedded IE for html-mail, then the exploit would be executed when the
    mail is html-rendered.
    
    As Eudora is more wide-spread this may be the worst exploit to a non-MS
    mail client that we have seen so far.
    
    It is not a bug of Eudora per se, but Eudora acts as a perfect
    trojan-injector which makes it very dangerous.
    
    Blocking or renaming executables on MTA-level will of course be a
    reasonable counter-measure for this problem.
    
    /magnus
    
    -- 
    http://x42.com/
    



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