Research Archives > Security Advisories > AD20020508

MSN Messenger OCX Buffer Overflow

Release Date:
5/8/2002 12:00:00 AM

Date Reported:
5/8/2002 12:00:00 AM

Severity:
High

Vendor:
Microsoft

Affected Software:
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

Overview:
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 control.

Technical Details:
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.

Example:

<object classid="clsid:9088E688-063A-4806-A3DB-6522712FC061" width="455" height="523">
<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]">
</object>

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 Microsoft.

Vulnerability identifier: CAN-2002-0155

Protection:
Microsoft has released a security bulletin and patch. For more information visit: http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/MS02-022.asp

Vendor Status:

Credit:
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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