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             AUSCERT External Security Bulletin Redistribution

           ESB-2002.122 -- Microsoft Security Bulletin MS02-014
      Unchecked Buffer in Windows Shell Could Lead to Code Execution
                               11 March 2002

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

Product:                Windows 98
                        Windows 98 Second Edition
                        Windows NT 4.0
                        Windows NT 4.0 Terminal Server
                        Windows 2000
Vendor:                 Microsoft
Impact:                 Execute Arbitrary Code/Commands
                        Denial of Service
Access Required:        Existing Account
                        Remote

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- ----------------------------------------------------------------------
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)

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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
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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.

- --------------------------END INCLUDED TEXT--------------------

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