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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