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             AUSCERT External Security Bulletin Redistribution

                          ESB-2008.0433 -- [Win]
          Microsoft HeartbeatCtl ActiveX control buffer overflow
                               30 April 2008


        AusCERT Security Bulletin Summary

Product:              HeartbeatCtl ActiveX control
Publisher:            US-CERT
Operating System:     Windows
Impact:               Execute Arbitrary Code/Commands
Access:               Remote/Unauthenticated
CVE Names:            CVE-2007-6255

Original Bulletin:    http://www.kb.cert.org/vuls/id/570089

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Vulnerability Note VU#570089

Microsoft HeartbeatCtl ActiveX control buffer overflow


The Microsoft HeartbeatCtl ActiveX control contains a buffer overflow, which
may allow a remote, unauthenticated attacker to execute arbitrary code on a 
vulnerable system. 

I. Description

The Microsoft HeartbeatCtl ActiveX control is used to play multiplayer games 
on the MSN Games website. The HeartbeatCtl ActiveX control contains a buffer 
overflow in the handling of the "Host" parameter.

II. Impact
By convincing a user to view a specially crafted HTML document (e.g., a web 
page or an HTML email message or attachment), an attacker may be able to 
execute arbitrary code with the privileges of the user.

III. Solution
Apply an update 
This issue is addressed in Microsoft Security Bulletin MS07-069. This update 
sets the kill bit for several unsupported versions of the HeartbeatCtl
ActiveX control.

Disable the HeartbeatCtl ActiveX control in Internet Explorer

The vulnerable ActiveX control can be disabled in Internet Explorer by setting 
the kill bit for the following CLSID:


More information about how to set the kill bit is available in Microsoft 
Support Document 240797. Alternatively, the following text can be saved as 
a .REG file and imported to set the kill bit for this control:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{E5D419D6-A846-4514-9FAD-97E826C84822}]
"Compatibility Flags"=dword:00000400

Disable ActiveX

Disabling ActiveX controls in the Internet Zone (or any zone used by an 
attacker) appears to prevent exploitation of this and other ActiveX
vulnerabilities. Instructions for disabling ActiveX in the Internet Zone can 
be found in the "Securing Your Web Browser" document.  

Systems Affected

Vendor                 Status      Date Updated 
Microsoft Corporation Vulnerable   21-Apr-2008 


This vulnerability was reported by Will Dormann of the CERT/CC. 

This document was written by Will Dormann. 

Other Information
Date Public 11/12/2007 
Date First Published 21/04/2008 05:29:07 PM 
Date Last Updated 21/04/2008 

CERT Advisory 
CVE Name CVE-2007-6255 
US-CERT Technical Alerts   
Metric 3.90 
Document Revision 6 

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