Microsoft Security Bulletin MS03-027: Unchecked Buffer in Windows Shell Could Enable System Compromise (Q821557)

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Title:      Unchecked Buffer in Windows Shell Could Enable System 
            Compromise (821557)
Date:       16 July 2003
Software:   Microsoft(r) Windows (r) XP 
Impact:     Run code of attacker's choice
Max Risk:   Important
Bulletin:   MS03-027

Microsoft encourages customers to review the Security Bulletins 
at: 
http://www.microsoft.com/technet/security/bulletin/MS03-027.asp
http://www.microsoft.com/security/security_bulletins/MS03-027.asp
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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. It 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 programs. 

An unchecked buffer exists in one of the functions used by the 
Windows shell to extract custom attribute information from 
certain folders. A security vulnerability results because it is 
possible for a malicious user to construct an attack that could 
exploit this flaw and execute code on the user's system. 

An attacker could seek to exploit this vulnerability by creating 
a Desktop.ini file that contains a corrupt custom attribute, and 
then host it on a network share. If a user were to browse the 
shared folder where the file was stored, the vulnerability could 
then be exploited. 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: 
====================

 - 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. 

 - An attacker could only seek to exploit this vulnerability by 
hosting a malicious file on a share. 

 - This vulnerability only affects Windows XP Service Pack 1. 
Users running Windows XP Gold are not affected. 

Risk Rating:
============
Important

Patch Availability:
===================
 - A patch is available to fix this vulnerability. Please read 
the  Security Bulletins at
   
http://www.microsoft.com/technet/security/bulletin/ms03-027.asp
http://www.microsoft.com/security/security_bulletins/ms03-027.asp
   
   for information on obtaining this patch.


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