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Title:      Flaw in Windows XP Help and Support Center Could Enable
            File Deletion (Q328940)
Date:       16 October 2002 
Software:   Microsoft Windows XP
Impact:     Delete files on the user's system
Max Risk:   Moderate
Bulletin:   MS02-060

Microsoft encourages customers to review the Security Bulletin at: 
http://www.microsoft.com/technet/security/bulletin/MS02-060.asp.
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Issue:
======
Help and Support Center provides a centralized facility through which
users can obtain assistance on a variety of topics. For instance, it
provides product documentation, assistance in determining hardware
compatibility, access to Windows Update, online help from Microsoft,
and other assistance. 

A security vulnerability is present in the Windows XP version of Help
and Support Center, and results because a file intended only for use
by the system is instead available for use by any web page. The
purpose of the file is to enable anonymous upload of hardware
information, with the user's permission, so that Microsoft can
evaluate which devices users are not currently finding device drivers
for. This information is then used to work with hardware vendors and
device teams to improve the quality and quantity of drivers available
in Windows. By design, after attempting to upload an XML file
containing the hardware information, the system deletes it. 

An attacker could exploit the vulnerability by constructing a web
page that, when opened, would call the errant function and supply the
name of an existing file or folder as the argument. The attempt to
upload the file or folder would fail, but the file nevertheless would
be deleted. The page could be hosted on a web site in order to attack
users visiting the site, or could be sent as an HTML mail in order to
attack the recipient when it was opened. 


Mitigating Factors:
====================
- - Customers who have applied Windows XP Service Pack 1 are at no risk
  from the vulnerability. 

- - The vulnerability could not be exploited without some degree of
  user interaction. Even in the most attacker-favorable case, the
  Help and Support Center window would appear unexpectedly and the
  file deletion could not occur until the user responded. (Even
  selecting Cancel, though, would enable the deletion to occur). If
  the user killed the process rather than responding, the deletion
  could not occur. 

- - For an attack to be successful, the user would need to visit a
  website under the attacker's control or receive an HTML e-mail
  from the attacker. 

- - The vulnerability would not enable an attacker to take any action
  other than deleting files. It would not grant any form of
  administrative control over the system, nor would it enable the
  attacker to read or modify files. 

- - The Help and Support Center function could not be started
  automatically in Outlook Express or Outlook if the user is running
  Internet Explorer 6.0 Service Pack 1, or in Outlook 2002 if "Read
  as Plain Text" is enabled. 

- - In order to delete a file, the attacker would need to know its
  exact file and path name. To delete a folder, the attacker would
  need to know its exact path. 

- - If the attacker used the vulnerability to disrupt system
  operation, Automatic System Recovery would provide a means of
  restoring normal operation. In addition, Windows XP will
  automatically restore many system files if deleted. 

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/ms02-060.asp
   for information on obtaining this patch.

Acknowledgment:
===============
 - Shane Hird of the Distributed Systems Technology Centre
   (http://security.dstc.edu.au)

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