Alert: Microsoft Security Bulletin - MS02-060

From: Russ (Russ.Cooper@RC.ON.CA)
Date: 10/17/02

Date:         Thu, 17 Oct 2002 08:25:24 -0400
From: Russ <Russ.Cooper@RC.ON.CA>

Flaw in Windows XP Help and Support Center Could Enable File Deletion (Q328940)

Originally posted: October 16, 2002


Who should read this bulletin: Customers using Microsoft® Windows® XP.

Impact of vulnerability: Delete files on the user's system.

Maximum Severity Rating: Moderate

Recommendation: Customers should install Windows XP Service Pack 1 as a first option, and install the patch only as an interim measure.

Affected Software:
- Microsoft Windows XP

Technical description:

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.

Vulnerability identifier: CAN-2002-0868

This email is sent to NTBugtraq automatically as a service to my subscribers. Since its programmatically created, and since its been a long time since anyone paid actual money for my programming skills, it may or may not look that good...;-]

I can only hope that the information it does contain can be read well enough to serve its purpose.

Russ - Surgeon General of TruSecure Corporation/NTBugtraq Editor

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