PROGRAM: Yahoo Instant Messenger (YIM)
VULNERABLE VERSIONS: 188.8.131.527 and below
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 :-).
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.
Yahoo has been contacted at firstname.lastname@example.org (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.
Discovered by Tri Huynh from SentryUnion
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