Procedure to Eliminate dvwssr.dll Vulnerability

According to an e-mail from Microsoft “A procedure is available” to eliminate the prior mentioned security vulnerability in several Microsoft web server products.

The vulnerability could allow a user who has privileges on a web server to read certain files from other web sites hosted on the same computer.

Frequently asked questions regarding this vulnerability and the procedure can be found

here.

The following is the text of the e-mail Microsoft sent out.

Issue
=====

Dvwssr.dll is a server-side component used to support the Link View feature in Visual Interdev 1.0. By design, it provides .asp files to
clients who have web authoring privileges on the server. However, it does not properly restrict the files that a web author can request,
with the result that a user who has web authoring privileges on one web site could request .asp files from anywhere on the server,
including other web sites hosted on it. However, even with this vulnerability, the component would only comply with the request if the specific file granted read access to the user.



There are some significant restrictions to this vulnerability:
- Only servers hosting multiple web sites could be affected by it
- Only a user who has web authoring privileges for a site on the server could request a file. He would need to know the name and location of the file on the server.
- The files would only be sent if their permissions granted read access to the particular user who requested them. In most cases, this would mean that the files granted read access to the Everyone group
- Only .asp files (and global.asa, which is a special-case .asp file) could be retrieved.



Affected Software Versions
==========================
The affected component is part of Visual Interdev 1.0. However, it is a server-side component, and is included in the following products:
- Windows NT 4.0 Option Pack
- Personal Web Server 4.0, which ships as part of Windows 95 and 98
- Front Page 98 Server Extensions

NOTE:
1. Windows 2000 is not affected by this vulnerability. Upgrading from an affected Windows NT 4.0 to Windows 2000 removes the vulnerability.

2. Installing Office 2000 Server Extensions on an affected server removes this vulnerability.

3. Installing FrontPage 2000 Server Extensions on an affected server removes this vulnerability.



Remediation
===========
To eliminate this vulnerability, customers who are hosting web sites should delete all copies of the file Dvwssr.dll from their servers.
The FAQ provides step-by-step instructions for doing this. The only functionality lost by deleting the file is the ability to generate
link views using Visual Interdev 1.0.