From secnotif@MICROSOFT.COM Wed Apr 21 18:35:05 1999 From: Microsoft Product Security To: MICROSOFT_SECURITY@ANNOUNCE.MICROSOFT.COM Date: Wed, 21 Apr 1999 13:41:19 -0700 Subject: Microsoft Security Bulletin (MS99-012) 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 (MS99-012) -------------------------------------- MSHTML Update Available for Internet Explorer Originally Posted: April 21, 1999 Summary ======= Microsoft has released an updated version of a component of Internet Explorer 4.0 and 5. The updated version eliminates three security vulnerabilities described below. It is fully supported and Microsoft recommends that affected customers download and install it, if appropriate. Issue ===== MSHTML.DLL is the parsing engine for HTML in Internet Explorer. The vulnerabilities that are eliminated by the update are not related to each other except for the fact that all reside within the parsing engine. - The first vulnerability is a privacy issue involving the processing of the "IMG SRC" tag in HTML files. This tag identifies and loads image sources - image files that are to be displayed as part of a web page. The vulnerability results because the tag can be used to point to files of any type, rather than only image files, after which point the document object model methods can be used to determine information about them. A malicious web site operator could use this vulnerability to determine the size and other information about files on the computer of a visiting user. It would not allow files to be read or changed, and the malicious web site operator would need to know the name of each file. - The second vulnerability is a new variant of a previously-identified cross-frame security vulnerability. A particular malformed URL could be used to execute scripts in the security context of a different domain. This could allow a malicious web site operator to execute a script on the web site, and gain privileges on visiting users' machines that are normally granted only to their trusted sites. - The third vulnerability affects only Internet Explorer 5.0, and is a new variant of a previously-identified untrusted scripted paste vulnerability. The vulnerability would allow a malicious web site operator to create a particular type of web page control and paste into it the contents of a visiting user's clipboard. While there are no reports of customers being adversely affected by any of these vulnerabilities, Microsoft is proactively releasing an updated version of MSHTML.DLL to allow customers to take appropriate action to protect themselves against it. Affected Software Versions ========================== - Internet Explorer 4.0 and 5 on Windows 95, Windows 98 and Windows NT 4.0. What Microsoft is Doing ======================= Microsoft has released patches that fix the problem identified. The patches are available for download from the sites listed below in What Customers Should Do. Microsoft also has sent this security bulletin to customers subscribing to the Microsoft Product Security Notification Service. See http://www.microsoft.com/security/services/bulletin.asp for more information about this free customer service. Microsoft has published the following Knowledge Base (KB) article on this issue: - Microsoft Knowledge Base (KB) article Q226326, Update Available for MSHTML Security Issues in Internet Explorer, http://support.microsoft.com/support/kb/articles/q226/3/26.asp. (Note: It might take 24 hours from the original posting of this bulletin for the KB article to be visible in the Web-based Knowledge Base.) What Customers Should Do ======================== Microsoft highly recommends that customers evaluate the degree of risk that this vulnerability poses to their systems and determine whether to download and install the patch. The patch can be found at http://www.microsoft.com/windows/ie/security/mshtml.asp. More Information ================ Please see the following references for more information related to this issue. - Microsoft Security Bulletin MS99-012, MSHTML Update Available for Internet Explorer (The Web-posted version of this bulletin), http://www.microsoft.com/security/bulletins/ms99-012.asp. - Microsoft Knowledge Base (KB) article Q226326, Update Available for MSHTML Security Issues in Internet Explorer, http://support.microsoft.com/support/kb/articles/q226/3/26.asp. - Microsoft Security Bulletin MS98-013, Fix available for Internet Explorer Cross Frame Navigate Vulnerability, http://www.microsoft.com/security/bulletins/ms98-013.asp - Microsoft Security Bulletin MS98-015, Update available for "Untrusted Scripted Paste" Issue in Microsoft Internet Explorer 4.01, http://www.microsoft.com/security/bulletins/ms98-015.asp Obtaining Support on this Issue =============================== If you require technical assistance with this issue, please contact Microsoft Technical Support. For information on contacting Microsoft Technical Support, please see http://support.microsoft.com/support/contact/default.asp. Acknowledgments =============== Microsoft acknowledges Richard M. Smith, President, Phar Lap Software, Inc., for discovering the IMG SRC vulnerability, and Georgi Guninski from TechnoLogica Ltd., Bulgaria, for discovering the cross-frame and untrusted scripted paste vulnerabilities. Revisions ========= - April 21, 1999: Bulletin Created. For additional security-related information about Microsoft products, please visit http://www.microsoft.com/security ---------------------------------------------------------------------- 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. ******************************************************************* 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. 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