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Microsoft Security Bulletin (MS00-037)
- --------------------------------------

Patch Available for "HTML Help File Code Execution" Vulnerability

Originally posted: June 02, 2000

Summary
=======
Microsoft has released a patch that eliminates a security
vulnerability in the HTML Help facility  that ships with Microsoft(r)
Internet Explorer. Under certain conditions, the vulnerability could
allow a malicious web site to take inappropriate action on the
computer of a visiting user.

Frequently asked questions regarding this vulnerability
and the patch can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-037.asp

Issue
=====
The HTML Help facility provides the ability to launch code via
shortcuts included in HTML Help  files. If a compiled HTML Help
(.chm) file were referenced by a malicious web site, it could
potentially be used to launch code on a visiting user's computer
without the user's approval.  Such code could take any actions that
the user could take, including adding, changing or deleting  data, or
communicating with a remote web site.

A web site could only invoke an HTML Help file if it resided on a UNC
share accessible from the  user's machine, or on the user's machine
itself. A firewall that blocks Netbios would prevent the  former case
from being exploited. Adhering to standard security practices would
prevent the  latter. In addition, an HTML Help file could only be
invoked if Active Scripting was permitted in  the Security Zone that
the malicious user's site resides in. The patch eliminates the
vulnerability by only allowing an HTML Help file to use shortcuts if
the help file resides on the  local machine.

Affected Software Versions
==========================
 - Microsoft Internet Explorer 4.0
 - Microsoft Internet Explorer 4.01
 - Microsoft Internet Explorer 5.0
 - Microsoft Internet Explorer 5.01

Patch Availability
==================
 - Internet Explorer 4.0, 4.01, 5.0, or 5.01 running on Windows 95,
   Windows 98, Windows 98 Second Edition, or Windows NT 4.0:
   http://www.microsoft.com/Downloads/Release.asp?ReleaseID=21705
 - Internet Explorer 5.01 on Windows 2000:
   http://www.microsoft.com/Downloads/Release.asp?ReleaseID=21706

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 MS00-037,
   http://www.microsoft.com/technet/security/bulletin/fq00-037.asp
 - Microsoft Knowledge Base article Q259166 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
===============================
This is a fully supported patch. Information on contacting Microsoft
Technical Support is available at
http://support.microsoft.com/support/contact/default.asp

Revisions
 - June 02, 2000: Bulletin Created.

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

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WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES  OF
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SHALL MICROSOFT CORPORATION  OR ITS SUPPLIERS BE LIABLE FOR ANY
DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
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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 June 02,2000

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

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