From secnotif@MICROSOFT.COM Sat Oct 16 13:59:49 1999 From: Microsoft Product Security Resent-From: mea culpa To: MICROSOFT_SECURITY@ANNOUNCE.MICROSOFT.COM Resent-To: jericho@attrition.org Date: Fri, 15 Oct 1999 14:57:54 -0700 Subject: Microsoft Security Bulletin (MS99-042) 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) -------------------------------------- Patch Available for "IFRAME ExecCommand" Vulnerability Originally Posted: October 11, 1999 Updated: October 15, 1999 Summary ======= On October 11, 1999, Microsoft released the original version of this bulletin, in order to advise customers of a workaround for a vulnerability in Microsoft(r) Internet Explorer. The vulnerability could allow a malicious web site operator to read files on the computer of a user who visited the site, under certain circumstances. 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/MS99-042faq.asp. Issue ===== The Internet Explorer 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. A patch that corrects this vulnerability is available at the location discussed below. This patch also includes the previously-released fix for the "Download Behavior" vulnerability. Affected Software Versions ========================== - Microsoft Internet Explorer 4.01, versions prior to Service Pack 2 - Microsoft Internet Explorer 5 Patch Availability ================== Internet Explorer 4.01 users should apply IE 4.01 Service Pack 2 at: - http://www.microsoft.com/windows/ie/download/windows.htm Internet Explorer 5 should apply that patch for this vulnerability at: - Intel Platform: ftp://ftp.microsoft.com/peropsys/IE/IE-Public/Fixes/ usa/IE50/MSHTML-fix/x86/q243638.exe - Alpha Platform: ftp://ftp.microsoft.com/peropsys/IE/IE-Public/Fixes/ usa/IE50/MSHTML-fix/Alpha/q243638.exe NOTE: Line breaks have been inserted into the URLs above to improve readability. NOTE: The IE5 patch also includes the previously-released fix for the "Download Behavior" vulnerability, discussed in http://www.microsoft.com/security/bulletins/ms99-040.asp. NOTE: The IE5 patch also will be available shortly at http://windowsupdate.microsoft.com. When this happens, this bulletin will be modified to provide the download location. 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 Knowledge Base (KB) article Q243638, Update Available for "IFRAME ExecCommand" Vulnerability in Internet Explorer 5, http://support.microsoft.com/support/kb/articles/q243/6/38.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 =============================== This is a fully supported patch. 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. - October 15, 1999: Bulletin re-released to provide information on 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. 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