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Re: [Full-Disclosure] Microsoft MCWNDX.OCX ActiveX buffer overflow
From: jelmer <jkuperus () planet nl>
Date: Wed, 13 Aug 2003 04:32:51 +0200

thats why they set kill bits

----- Original Message ----- 
From: "Thor Larholm" <thor () pivx com>
To: "Tri Huynh" <trihuynh () zeeup com>; <bugtraq () securityfocus com>
Cc: <full-disclosure () lists netsys com>
Sent: Wednesday, August 13, 2003 8:21 PM
Subject: Re: [Full-Disclosure] Microsoft MCWNDX.OCX ActiveX buffer overflow

The MCWNDX.OCX binary is digitally signed by Microsoft, and as such you
plant it on the users machine just by pointing the codebase attribute of
OBJECT tag to an archived copy of the file on your own server.

This also applies to other outdated ActiveX controls, even when a newer
(patched)  version exists and is installed on the users machine you can
re-introduce the old, buggy version since it is digitally signed by

Thor Larholm
PivX Solutions, LLC - Senior Security Researcher

----- Original Message ----- 
From: "Tri Huynh" <trihuynh () zeeup com>
Subject: [Full-Disclosure] Microsoft MCWNDX.OCX ActiveX buffer overflow

 Microsoft MCWNDX.OCX ActiveX buffer overflow

HOMEPAGE:  www.microsoft.com
VULNERABLE VERSIONS: MCWNDX is an ActiveX shipped with Visual Studio 6
support multimedia programming.


 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)

 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
is good enough :-) ), it will cause a bufferoverflow. (I can't overwrite
EIP using this overflow in my XP, however it doesn't mean the problem
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 !"


 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


 Discovered by Tri Huynh from Sentry Union


 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.


 Please send suggestions, updates, and comments to: trihuynh () zeeup com

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