Microsoft Security Bulletin (MS00-025)

[secnotif () MICROSOFT COM (Microsoft Product Security)]

The following is a Security  Bulletin from the Microsoft Product Security
Notification Service.

Please do not  reply to this message,  as it was sent  from an unattended
mailbox.
                    ********************************

-----BEGIN PGP SIGNED MESSAGE-----

Microsoft Security Bulletin (MS00-025)
- --------------------------------------

Procedure Available to Eliminate "Link View Server-Side Component"
Vulnerability

Originally Posted: April 14, 2000
Updated: April 17, 2000

Summary
=======
On April 14, 2000, Microsoft issued the original version of this
bulletin, to discuss a security vulnerability affecting  several web
server products. Shortly after publishing the bulletin, we learned of
a new, separate vulnerability that  increased the threat to users of
these products. We updated the bulletin later on April 14, 2000, to
advise customers of the  new vulnerability, and noted that we would
provide additional details when known. On April 17, 2000, we updated
the bulletin  again to provide those details.

A procedure is available to eliminate a security vulnerability that
could allow a malicious user to cause a web server to  crash, or
potentially run arbitrary code on the server, if certain permissions
have been changed from their default settings  to inappropriate ones.
Although this bulletin has been updated several times as the
investigation of this issue has  progressed, the remediation steps
have always remained the same - customers running affected web servers
should delete the  affected file, Dvwssr.dll. Customers who have done
this at any point in the past do not need to take any further action.

Frequently asked questions regarding this vulnerability and
the procedure can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-025.asp

Issue
=====
Dvwssr.dll is a server-side component used to support the Link View
feature in Visual Interdev 1.0. However, it contains an  unchecked
buffer. If overrun with random data, it could be used to cause an
affected server to crash, or could allow  arbitrary code to run on the
server in a System context.

By default, the affected component, Dvwssr.dll, resides in a folder
whose permissions only allow web authors to execute it.  Under these
conditions, only a person with web author privileges could exploit the
vulnerability - but a web author already  has the ability to upload
and execute code of his choice, so this case represents little
additional threat. However, if the  permissions on the folder were set
inappropriately, or the .dll were copied to a folder with lower
permissions, it could be  possible for other users to execute the
component and exploit the vulnerability.

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:
 - Microsoft(r) Windows NT(r) 4.0 Option Pack, which is the
   primary distribution mechanism for Internet Information
   Server 4.0
 - Personal Web Server 4.0, which ships as part of
   Windows(r) 95 and 98
 - Front Page 98 Server Extensions, which ships as part of
   Front Page 98.

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
using any of the affected products 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 of .asp pages using
Visual Interdev 1.0.

More Information
================
Please see the following references for more information related to
this issue.
 - Frequently Asked Questions: Microsoft Security Bulletin MS00-025,
   http://www.microsoft.com/technet/security/bulletin/fq00-025.asp.
 - Microsoft Knowledge Base article Q259799 discusses this issue and
   will be available soon.
 - Microsoft TechNet Security web site,
   http://www.microsoft.com/technet/security/default.asp.

Obtaining Support on this Issue
===============================
Information on contacting Microsoft Technical Support is available
at http://support.microsoft.com/support/contact/default.asp.

Revisions
=========
 - April 14, 2000: Bulletin Created.
 - April 14, 2000: Bulletin updated to provide preliminary results
   of investigation of buffer overrun vulnerability.
 - April 17, 2000: Bulletin updated to provide final results of
   investigation.

- ----------------------------------------------------------------

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 ANY DAMAGES
WHATSOEVER INCLUDING DIRECT,  INDIRECT, INCIDENTAL, CONSEQUENTIAL,
LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF 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.

Last updated April 17, 2000

(c) 2000 Microsoft Corporation. All rights reserved. Terms of use.

-----BEGIN PGP SIGNATURE-----
Version: PGP 6.0.2

iQEVAwUBOPtK540ZSRQxA/UrAQFLNAf/f+J9Gu2bLni4x+CD2TxY4LZXsCLGkQgq
hXiEcNVlqccSClIRg84zlYL2KDGkDCwQWtE8JR93V0MkirOdpY9rCW39DWCzJxo0
2wKI9NaPJl8cgbMiFWpRErw8ojHoX+fgtWqBGbGnZPxShCmQOVh/xBLvjCz1KakZ
GrzNecfyK58aT3Ao2w8uxAfLp8z0Kzuaj+YYmkLq36/TPUkBmBJHsDOBP++3WoDA
1Dxe9/zahwMd7wwtwdQGtFUD9iQYVB3zd8QnYZCiwUOJR6fLc2nsj4AtylFynqRD
Mg4lsvMjDzHZj6p5JMbxpzebymWTjPgTd5hr66ZBdtb8CdwisV/oig==
=6B1q
-----END PGP SIGNATURE-----

   *******************************************************************
You have received  this e-mail bulletin as a result  of your registration
to  the   Microsoft  Product  Security  Notification   Service.  You  may
unsubscribe from this e-mail notification  service at any time by sending
an  e-mail  to  MICROSOFT_SECURITY-SIGNOFF-REQUEST () ANNOUNCE MICROSOFT COM
The subject line and message body are not used in processing the request,
and can be anything you like.

To verify the digital signature on this bulletin, please download our PGP
key at http://www.microsoft.com/technet/security/notify.asp.

For  more  information on  the  Microsoft  Security Notification  Service
please  visit  http://www.microsoft.com/technet/security/notify.asp.  For
security-related information  about Microsoft products, please  visit the
Microsoft Security Advisor web site at http://www.microsoft.com/security.