IE5_download_vuln.txt

1999-10-12T00:00:00
ID PACKETSTORM:16335
Type packetstorm
Reporter Packet Storm
Modified 1999-10-12T00:00:00

Description

                                        
                                            `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 (MS99-040)  
--------------------------------------  
  
Patch Available for "Download Behavior" Vulnerability  
Originally Posted: September 28, 1999  
Updated: October 08, 1999  
  
Summary  
=======  
On September 28, 1999, Microsoft released the original version of this  
bulletin, in order to provide a workaround for a security vulnerability in  
Microsoft(r) Internet Explorer 5 that could allow a malicious web site  
operator to read files on the computer of a person who visited the site.  
Microsoft has completed a patch that completely eliminates the  
vulnerability, and has re-released this bulletin in order to advise  
customers of its availability.  
  
Frequently asked questions regarding this vulnerability can be found  
at http://www.microsoft.com/security/bulletins/MS99-040faq.asp.  
  
Issue  
=====  
IE 5 includes a feature called "download behavior" that allows web page  
authors to download files for use in client-side script. By design, a web  
site should only be able to download files that reside in its domain; this  
prevents client-side code from exposing files on the user's machine or  
local intranet to the web site. However, a server-side redirect can be used  
to bypass this restriction, thereby enabling a malicious web site operator  
to read files on the user's machine or the user's local intranet. This  
vulnerability would chiefly affect workstations that are connected to the  
Internet.  
  
Affected Software Versions  
==========================  
- Microsoft Internet Explorer 5  
  
Patch Availability  
==================  
The patch is available for download at either of the following locations  
- http://windowsupdate.microsoft.com  
- http://www.microsoft.com/msdownload/iebuild/dlbhav/en/dlbhav.htm  
  
More Information  
================  
Please see the following references for more information related to this  
issue.  
- Microsoft Security Bulletin MS99-040: Frequently Asked Questions,  
http://www.microsoft.com/security/bulletins/ms99-040faq.asp.  
- Microsoft Knowledge Base (KB) article Q242542,  
"Download Behavior" Vulnerability in Internet Explorer 5,  
http://support.microsoft.com/support/kb/articles/Q242/5/42.asp.  
(Note: It may take 24 hours from the original posting of this  
bulletin for this KB article to be visible.)  
- Microsoft Security Advisor web site,  
http://www.microsoft.com/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.  
  
Acknowledgments  
===============  
Microsoft acknowledges Georgi Guninski for bringing this issue to our  
attention.  
  
Revisions  
=========  
- September 28, 1999: Bulletin Created.  
- October 08, 1999: Bulletin updated to announce availability of patch.  
  
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