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. ----------------------------------------------------------------------- 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-REQUEST@ANNOUNCE.MICROSOFT.COM 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.