-----BEGIN PGP SIGNED MESSAGE-----

- ----------------------------------------------------------------------
Title:      Unchecked Buffer in Windows Shell Could Lead to Code
            Execution
Date:       07 March 2002
Software:   Microsoft Windows 98, NT 4.0, 2000
Impact:     Run code of attacker's choice
Max Risk:   Moderate
Bulletin:   MS02-014

Microsoft encourages customers to review the Security Bulletin at: 
http://www.microsoft.com/technet/security/bulletin/MS02-014.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 that helps to
locate incompletely removed applications on the system.
A security vulnerability results because it is possible for a
malicious user to mount a buffer overrun attack and attempt to
exploit this flaw.  A successful attack would have the affect
of either causing the Windows Shell to crash, or causing code
to run in the user's context.

Be default, this is not remotely exploitable.  However, under
very unusual conditions, it could be exploited via a web page
- - specifically, if the user has installed an application with
custom URL handlers and then uninstalled that application, and
the uninstall failed to correctly remove the application
completely.  An attacker could then attempt to levy an attack
by constructing an HTML web page that seeks to exploit the
vulnerability, and then posting it on their web site or
sending it by email.

Mitigating Factors:
====================
 - In a default installation, this vulnerability is not remotely
   exploitable and could only be exploited by introducing hostile
   code to the system.

 - The vulnerability can be remotely exploited only on machines
   that have installed and uninstalled software which implements
   customer URL handlers and the software's uninstall failed to
   completely remove the application from the system.

 - 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. As a result, customers
   using these products would not be at risk from email-borne
   attacks. 

 - The buffer overrun would allow code to run in the security
   context of the user rather than the system. The specific
   privileges the attacker could gain through this vulnerability
   would therefore depend on the privileges accorded to the user.

Risk Rating:
============
 - Internet systems: Low
 - Intranet systems: Low
 - Client systems: Moderate

Patch Availability:
===================
 - A patch is available to fix this vulnerability. Please read the 
   Security Bulletin at
   http://www.microsoft.com/technet/security/bulletin/ms02-014.asp
   for information on obtaining this patch.

Acknowledgment:
===============
- - eEye Digital Security (http://www.eeye.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.

-----BEGIN PGP SIGNATURE-----
Version: PGP 7.1

iQEVAwUBPIa1KY0ZSRQxA/UrAQEXOgf9EwxTGae/jFWxKs0TZVBGVPmd6YkVQUw8
O++3acyqNMrXnPj5PhMlIMllqo3Znh8OmXrPBsnrDyshG3Ok8zTiTx5QFULSm/P6
kSPNaD892kPdmvbxh98Wk+GWxcOKtLdwfUV9II/iCcBby3Plg8HtYPJZ+y/jdXdF
0qRnFTbh6T4DtS+yM8PrqMIvLfk3IuPpKVrxXkFyeV3VwLT2It8TEn69d63CfJoL
8gj1Ul0ghy+KVIMlKppVJuLZ1nd1W3bJNQlmWcn6rB7+UP+NqfA+Xn1CPCjEKDSo
qC0I1wciCXGb3dGe+2NeKN6QuGtoVokrNCyDZDFXmbRH/wvABU0liA==
=KWRD
-----END PGP SIGNATURE-----


*******************************************************************

You have received this e-mail bulletin as a result of your subscription to the Microsoft Product Security Notification   Service.  For more information on this service, please visit http://www.microsoft.com/technet/security/notify.asp.

To verify the digital signature on this bulletin, please download our PGP key at http://www.microsoft.com/technet/security/notify.asp.

To cancel your subscription, click on the following link mailto:1_26889_597AAC3D-B8D9-4A9A-A29A-9EBCF4758F48_US@Newsletters.Microsoft.com?subject=UNSUBSCRIBE to create an unsubscribe e-mail.

To stop all e-mail newsletters from microsoft.com, click on the following link mailto:2_26889_597AAC3D-B8D9-4A9A-A29A-9EBCF4758F48_US@Newsletters.Microsoft.com?subject=STOPMAIL to create an unsubscribe e-mail.  You can manage all your Microsoft.com communication preferences from http://www.microsoft.com/misc/unsubscribe.htm

For security-related information about Microsoft products, please  visit the Microsoft Security Advisor web site at http://www.microsoft.com/security.