[ISN] ADVISORY: MSN Messenger OCX Buffer Overflow

From: InfoSec News (isnat_private)
Date: Thu May 09 2002 - 00:06:26 PDT

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    From: "Marc Maiffret" <marcat_private>
    MSN Messenger OCX Buffer Overflow
    Release Date:
    High (Remote code execution)
    Systems Affected:
    Microsoft MSN Chat Control
    Microsoft MSN Messenger 4.5 and 4.6, which includes the MSN Chat
    control Microsoft Exchange Instant Messenger 4.5 and 4.6, which
    includes the MSN Chat control
    A vulnerability has been discovered in the parameter handling of the
    MSN Messenger OCX. By exploiting this vulnerability, an attacker can
    supply and execute code on any machine on which MSN Messenger with the
    activex is installed.
    The vulnerability exists because of how MSN Messenger handles data
    passed to it which can lead to a buffer overflow scenario. The buffer
    overflow can be exploited via email, web, or through any other method
    where Internet Explorer is used to display HTML that an attacker
    supplies, including software that uses the web browser ActiveX
    All users of Internet Explorer are potentially affected because this
    is a Microsoft signed OCX. Users that have not installed Microsoft
    Messenger or that have not upgraded Microsoft Messenger can only be
    affected if they accept the pop-up "Install Now" signed by Microsoft.
    All Internet Explorer users should install the update.
    <object classid="clsid:9088E688-063A-4806-A3DB-6522712FC061" width="455"
    <param name="_cx" value="12039">
    <param name="_cy" value="13838">
    <param name="BackColor" value="50331647">
    <param name="ForeColor" value="43594547">
    <param name="RedirectURL" value="">
    <param name="ResDLL" value="AAAAAAA[27,257 bytes is where the EIP starts]">
    Technical Description:
    MSNChat ocx is an ActiveX object installed with Microsoft Messenger.
    Proper bounds checking is not in place in the ResDLL parameter. By
    supplying a very large buffer, we can overwrite a significant portion
    of the stack, including saved return addresses and exception handlers.
    Even if users do not have Messenger installed, the ActiveX can be
    called from the codebase tag which would prompt the user to install
    the ActiveX with Microsoft's credentials because the OCX is signed by
    Vulnerability identifier: CAN-2002-0155
    Vendor Status:
    Microsoft has released a security bulletin and patch. For more information
    Discovery: Drew Copley
    Greetings: Mom, Dad, and all of the little people that helped me and
    believed in me - oh - and a big YO HO to the homeboyz in the h00d.
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