From secnotif@MICROSOFT.COM Wed Apr 21 18:35:02 1999 From: Microsoft Product Security To: MICROSOFT_SECURITY@ANNOUNCE.MICROSOFT.COM Date: Wed, 21 Apr 1999 13:40:33 -0700 Subject: Microsoft Security Bulletin (MS99-011) 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 (MS99-011) -------------------------------------- Patch Available for "DHTML Edit" Vulnerability Originally Posted: April 21, 1999 Summary ======= Microsoft has released a patch that eliminates a vulnerability in an ActiveX control that is distributed in Internet Explorer 5 and downloadable for Internet Explorer 4.0. The vulnerability could allow a malicious web site operator to read information that a user had loaded into the control, and it also could allow files with known names to be copied from the user's local hard drive. A fully supported patch is available to eliminate this vulnerability and Microsoft recommends that affected customers download and install it, if appropriate. Issue ===== The DHTML Edit control is an ActiveX control that is distributed with Internet Explorer 5 and can be downloaded for use in Internet Explorer 4.0. The control enables users to edit HTML text and see a faithful rendition of how the text would look in the browser. There are two versions of the control: a more powerful version that cannot be invoked by a web site because it includes file access and other features, and a "safe for scripting" version that has restricted functionality and is intended for use by web sites. The root cause of the vulnerability lies in the fact that a web site that hosts the "safe for scripting" version of the control is able to upload any data entered into the control. A malicious web site operator could trick a user into entering sensitive data into a DHTML Edit control hosted on a web page from the operator's site, and then upload the data. In addition, if the malicious web site operator knows the name of a file on the user's local drive, it is possible for the operator to programmatically load the file into the control and then upload it. The patch works by allowing a web site to load data from the control only if it is in the site's domain. While there are no reports of customers being adversely affected by this vulnerability, Microsoft is proactively releasing this patch to allow customers to take appropriate action to protect themselves against it. Affected Software Versions ========================== - Microsoft Internet Explorer 5 on Windows 95, Windows 98, and Windows NT 4.0. Internet Explorer 5 on other platforms is not affected. - Microsoft Internet Explorer 4.0 on Windows 95, Windows 98 and the x86 version of Windows NT 4.0. Internet Explorer 4.0 on other platforms, including the Alpha version of Windows NT 4.0, is not affected. Note: The DHTML Edit control is included by default in Internet Explorer 5. It is not included by default in Internet Explorer 4.0, but can be downloaded and installed. Internet Explorer 4.0 customers who are unsure whether they have installed the control should see What Customers Should Do. 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 'DHTML Edit' Security Issue, 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 determine whether they are potentially affected by the vulnerability: - All copies of Internet Explorer 5 contain the DHTML Edit control, so all Internet Explorer 5 customers are potentially affected by the vulnerability. - The only Internet Explorer 4.0 users who are potentially affected by the vulnerability are those who have downloaded and installed the DHTML Edit control. If this has been done, the file dhtmled.ocx will be present on the hard drive. By default, this file will be stored in the folder C:\Program Files\Common Files\Microsoft Shared\Triedit\. Customers who are potentially affected by the vulnerability should 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/dhtml_edit.asp. More Information ================ Please see the following references for more information related to this issue. - Microsoft Security Bulletin MS99-011, Patch Available for DHTML Edit Vulnerability. (The Web-posted version of this bulletin), http://www.microsoft.com/security/bulletins/ms99-011.asp. - Microsoft Knowledge Base (KB) article Q226326, Update Available for 'DHTML Edit' Security Issue, 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.) 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 Juan Carlos Cuartango of Spain for discovering this vulnerability and reporting it to us. 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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