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.
********************************
Microsoft Security Bulletin (MS99-042)
--------------------------------------
Workaround Available for "IFRAME ExecCommand" Vulnerability
Originally Posted: October 11, 1999
Summary
=======
Microsoft has learned of a vulnerability in Microsoft(r) Internet Explorer 5
that could allow a malicious web site operator to read files on the
computer of a user who visited the site, under certain circumstances.
Microsoft is developing a patch that will eliminate the vulnerability; in
the meantime, a temporary workaround is discussed below.
Frequently asked questions regarding this vulnerability can be found
at http://www.microsoft.com/security/bulletins/MS99-042faq.asp.
Issue
=====
The IE 5 security model normally restricts the Document.ExecCommand() method
to prevent it from taking inappropriate action on a user's computer.
However, at least one of these restrictions is not present if the method is
invoked on an IFRAME. This could allow a malicious web site operator to
read the contents of files on visiting users' computers, if he or she knew
the name of the file and the folder in which it resided. The vulnerability
would not allow the malicious user to list the contents of folders, create,
modify or delete files, or to usurp any administrative control over the
machine.
Affected Software Versions
==========================
- Microsoft Internet Explorer 5
Workaround
==========
As an interim step while the patch is under development, Microsoft
recommends that customers add sites that they trust to the Trusted Zone,
and disable Active Scripting in the Internet Zone. This will provide full
functionality for all trusted sites, while preventing untrusted sites from
being able to exploit this vulnerability. The FAQ provides details on how to
do this, and how to manage Security Zones in general.
More Information
================
Please see the following references for more information related to this
issue.
- Microsoft Security Bulletin MS99-042: Frequently Asked Questions,
http://www.microsoft.com/security/bulletins/MS99-042faq.asp.
- Microsoft Security Advisor web site,
http://www.microsoft.com/security/default.asp.
Obtaining Support on this Issue
===============================
This is a fully supported workaround. Information on contacting
Microsoft Technical Support is available at
http://support.microsoft.com/support/contact/default.asp.
Acknowledgments
===============
Microsoft acknowledges Georgi Guninski for bringing this issue to our
attention.
Revisions
=========
- October 11, 1999: Bulletin Created.
----------------------------------------------------------------------
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.
(c) 1999 Microsoft Corporation. All rights reserved. Terms of Use
*******************************************************************
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-REQUESTat_private
The subject line and message body are not used in processing the request,
and can be anything you like.
For more information on the Microsoft Security Notification Service
please visit http://www.microsoft.com/security/services/bulletin.asp. For
security-related information about Microsoft products, please visit the
Microsoft Security Advisor web site at http://www.microsoft.com/security.
This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 15:07:10 PDT