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===========================================================================
             AUSCERT External Security Bulletin Redistribution

           ESB-2002.709 -- Microsoft Security Bulletin MS02-072
     Unchecked Buffer in Windows Shell Could Enable System Compromise
                                 (Q329390)
                             19 December 2002

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:                Windows Shell
Vendor:                 Microsoft
Operating System:       Windows XP Home Edition
                        Windows XP Professional
                        Windows XP Tablet PC Edition
                        Windows XP Media Center Edition
Platform:               i386
                        IA-64
Impact:                 Administrator Compromise
                        Execute Arbitrary Code/Commands
                        Denial of Service
Access Required:        Remote

Comment: The Microsoft PGP signature is bad for this bulletin, however
         the details have been verified against the official Microsoft
         web site.

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- - ----------------------------------------------------------------------
Title:      Unchecked Buffer in Windows Shell Could Enable System 
Compromise (329390)
Date:       18 December 2002
Software:   Microsoft Windows XP
Impact:     Run code of an attacker's choice 
Max Risk:   Critical
Bulletin:   MS02-072

Microsoft encourages customers to review the Security Bulletins at: 
http://www.microsoft.com/technet/security/bulletin/MS02-072.asp
http://www.microsoft.com/security/security_bulletins/ms02-072.asp
- - ----------------------------------------------------------------------

Issue:
======
The Windows Shell is responsible for providing the basic framework
of the Windows user interface experience. It is most familiar to
users as the Windows Desktop, but also provides a variety of other
functions to help define the user's computing session, including
organizing files and folders, and providing the means to start
applications. 

An unchecked buffer exists in one of the functions used by the
Windows Shell to extract custom attribute information from audio
files. A security vulnerability results because it is possible
for a malicious user to mount a buffer overrun attack and attempt
to exploit this flaw. 

An attacker could seek to exploit this vulnerability by creating
an .MP3 or .WMA file that contained a corrupt custom attribute
and then host it on a website, on a network share, or send it via
an HTML email. If a user were to hover his or her mouse pointer
over the icon for the file (either on a web page or on the local
disk), or open the shared folder where the file was stored, the
vulnerable code would be invoked. An HTML email could cause the
vulnerable code to be invoked when a user opened or previewed the
email. A successful attack could have the effect of either causing
the Windows Shell to fail, or causing an attacker's code to run on
the user's computer in the security context of the user.


Mitigating Factors:
====================
 - The vulnerability lies in the Windows Shell, rather than Windows
   Media Player. As a result, playing an audio file with Windows
   Media Player would not pose any additional risk. 

 - Outlook 98 and 2000 (after installing the Outlook Email Security
   Update),Outlook 2002, and Outlook Express 6 all open HTML mail in 
   the Restricted Sites Zone. Customers who are using these products
   and who have also installed Windows XP Service Pack 1 or any 
   recent security patch for Internet Explorer that disables frames
   in the Restricted Sites zone would not be at risk from automated
   email-borne attacks. However, these customers could still be
   attacked if they choose to click on a hyperlink in a malicious
   HTML email.
 
 - In the case where an attacker's code was executed, the code 
   would run in the security context of the user. As a result,
   any limitations on the user's ability would also restrict the
   actions that an attacker's code could take. 

Risk Rating:
============
 - Windows XP: Critical 

Patch Availability:
===================
 - A patch is available to fix this vulnerability. Please read the 
   Security Bulletin at
   http://www.microsoft.com/technet/security/bulletin/ms02-072.asp
   for information on obtaining this patch.

Acknowledgment:
===============
 - Foundstone Research Labs (http://www.foundstone.com)

- - ---------------------------------------------------------------------

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS 
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS
ALL 
WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE 
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
IN NO EVENT 
SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY
DAMAGES 
WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL,
LOSS OF 
BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR
ITS 
SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME
STATES DO 
NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL
OR 
INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

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