Microsoft Security Bulletin (MS00-006)

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Microsoft Security Bulletin (MS00-006)
--------------------------------------

Patch Available for "Malformed Hit-Highlighting Argument" Vulnerability

Originally Posted: January 26, 2000

Summary
=======

Microsoft has released a patch that eliminates two security vulnerabilities
in Microsoft(r) Index  Server. The first vulnerability could allow a
malicious user to view -- but not to change, add or  delete -- files on a
web server. The second vulnerability could reveal where web directories are
physically located on the server.

Frequently asked questions regarding this vulnerability and the patch can be
found at
http://www.microsoft.com/technet/security/bulletin/fq00-006.asp

Issue
=====
This patch eliminates two vulnerabilities whose only relationship is that
both occur in Index  Server. The first is the "Malformed Hit-Highlighting
Argument" vulnerability. The ISAPI filter  that implements the
hit-highlighting (also known as "WebHits") functionality does not adequately
constrain what files can be requested. By providing a deliberately-malformed
argument in a  request to hit-highlight a document, it is possible to escape
the virtual directory. This would  allow any file residing on the server
itself, and on the same logical drive as the web root  directory, to be
retrieved regardless of permissions.

The second vulnerability involves the error message that is returned when a
user requests a  non-existent Internet Data Query file. The error message
provides the physical path to the web  directory that was contained in the
request. Although this vulnerability would not allow a  malicious user to
alter or view any data, it could be a valuable reconnaissance tool for
mapping  the file structure of a web server.

Affected Software Versions
==========================
 - Microsoft Index Server 2.0
 - Indexing Service in Windows 2000

Patch Availability
==================
Index Server 2.0:
 - Intel:
   http://www.microsoft.com/downloads/release.asp?ReleaseID=17727
 - Alpha:
   http://www.microsoft.com/downloads/release.asp?ReleaseID=17728

Indexing Services for Windows 2000:
 - Intel:
   http://www.microsoft.com/downloads/release.asp?ReleaseID=17726

NOTE: Additional security patches are available at the Microsoft Download
Center

More Information
================
Please see the following references for more information related to this
issue.
 - Frequently Asked Questions: Microsoft Security Bulletin MS00-006,
   http://www.microsoft.com/technet/security/bulletin/fq00-006.asp.
 - Microsoft Knowledge Base (KB) article Q251170,
   Malformed Argument in Hit-Highlighting Request Allows Access
   to Web Server Files,
   http://www.microsoft.com/technet/support/kb.asp?ID=251170.
 - Microsoft Knowledge Base (KB) article Q252463,
   Index Server Error Message Reveals Physical Location of Web
   Directories,
   http://www.microsoft.com/technet/support/kb.asp?ID=252463.
 - Microsoft TechNet Security web site,
   http://www. microsoft.com/technet/security.

(Note: It may take 24 hours from the original posting of this bulletin for
the above KB articles  to be visible.)

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

Acknowledgments
===============
Microsoft thanks David Litchfield of Cerberus Information Security,
Ltd (http://www.cerberus-infosec.co.uk) for reporting the
"Malformed Hit-Highlighting Argument" vulnerability to us and
working with us to protect customers.

Revisions
=========
 - January 26, 2000: Bulletin Created.

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

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(c) 2000 Microsoft Corporation. All rights reserved.

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