Yahoo Instant Messenger YAUTO.DLL buffer overflow
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PROGRAM: Yahoo Instant Messenger (YIM)
HOMEPAGE: https://messenger.yahoo.com
VULNERABLE VERSIONS: 5.6.0.1347 and below


DESCRIPTION
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YIM is one of the most popular instant messenger. This is a cool product,
that allows me to chat with my gf from a very long distant :-).


DETAILS
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YAUTO.DLL is an ActiveX/COM component that comes with Yahoo
Install Messenger. YAUTO.DLL is registered under a ProgID called
"YAuto.NSAuto.1". In this component, there is a function named
Open(String Url) that will cause a buffer overflow if argument Url is passed
with
a long string. Since this is an ActiveX component, the vulnerability can
be exploited just by making a website with the correct CLSID of
the ActiveX and call the function directly. We have successfully exploited
the vulnerability by making a website that can download a trojan and
execute it silently.



WORKAROUND
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Yahoo has been contacted at enterprisesales@yahoo-inc.com (this
is the only email that I can find on the Yahoo Messenger Site) but
doesn't response after 1 month. The workaround solution is deleting
the YAUTO.DLL file in your YIM directory.


CREDITS
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Discovered by Tri Huynh from SentryUnion


DISLAIMER
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The information within this paper may change without notice. Use of
this information constitutes acceptance for use in an AS IS condition.
There are NO warranties with regard to this information. In no event
shall the author be liable for any damages whatsoever arising out of
or in connection with the use or spread of this information. Any use
of this information is at the user's own risk.


FEEDBACK
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Please send suggestions, updates, and comments to: trihuynh@zeeup.com