Microsoft MCWNDX.OCX ActiveX buffer overflow ================================================= PROGRAM: MICROSOFT MCIWNDX.OCX ACTIVEX BUFFER OVERFLOW HOMEPAGE: www.microsoft.com VULNERABLE VERSIONS: MCWNDX is an ActiveX shipped with Visual Studio 6 to support multimedia programming. DESCRIPTION ================================================= MCWNDX is an activeX shipped with Visual Studio 6 to support multimedia programming. Although not many people use it anymore, however it still can be called through CLSID in a website and passing a large amount of data to the activex will cause an buffer overflow. Since this Activex is only shipped with VIsual Studio 6.0, so only people who are having Visual Studio 6.0 will be affected or people who are still using old multimedia programs coded in Visual Studio 6.0 (In my PC, the last date the ActiveX is patched is in 1996 ! I am using VS Sp 4) DETAILS ================================================= The ActiveX has a property called "Filename" which is used to specify the .mci file to load. However if it is passed with a very large string(640KB is good enough :-) ), it will cause a bufferoverflow. (I can't overwrite the EIP using this overflow in my XP, however it doesn't mean the problem can't be exploited) Microsoft has been noticed but since the hole is maybe minor to them so they don't response to me even a short sentence like "Thank you !" WORKAROUND ================================================= Delete the file MCWNDX.ocx in your SYSTEM32 directory if you are using 2000 or XP or in your SYSTEM directory if you are using WIN ME or below CREDITS ================================================= Discovered by Tri Huynh from Sentry Union DISLAIMER ================================================= 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 ================================================= Please send suggestions, updates, and comments to: trihuynh@zeeup.com
