-----BEGIN PGP SIGNED MESSAGE----- __________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft: Vulnerabilities in Internet Explorer May 18, 2000 22:00 GMT Number K-044 ______________________________________________________________________________ PROBLEM: Microsoft has released a bulletin addressing three unrelated vulnerabilities in Internet Explorer. (1.) The "Frame Domain Verification" vulnerablity may allow a malicious web site operator to read files from a visiting user's computer. (2.) The "Unauthorized Cookie Access" vulnerability may allow a malicious web site operator to change or add cookies to a visiting user's computer. (3.) The "Malformed Component Attribute" vulnerability is a buffer overrun which may allow a malicious web site operator to run code of their choice on a visiting users computer. PLATFORM: Microsoft Internet Explorer 4.0, 4.01, 5.0, and 5.01. DAMAGE: (1.) The "Frame Domain Verification" vulnerability could allow a malicious web site operator to read .txt, .htm or .js files on a visiting user's computer. (2.) The "Unauthorized Cookie Access" vulnerability could entice a visiting user to click on a link that would allow the malicious web site operator to obtain personal information from the cookies stored on the user's computer. (3.) The "Malformed Component Attribute" vulnerability could allow a malicious web site operator to run code on a visiting user's computer which could add, change or delete data or reformat the user's hard disk. SOLUTION: Load the patch and use the Internet Explorer Security Zone (Tools/Internet Options/Security) to increase the web browsers security. ______________________________________________________________________________ VULNERABILITY With the first two vulnerabilities, "Frame Domain Verification" ASSESSMENT: and "Unauthorized Cookie Access" a user would need to visit a malicious web site. Most users visit a small number of professionally-operated sites which would make the risk LOW. As a user browsed more unfamiliar sites the risk would increase. The "Malformed Component Attribute" could be sent through e-mail, thus making the risk MEDIUM for this vulnerability. ______________________________________________________________________________ [****** Start Microsoft Bulletin ******] - -----BEGIN PGP SIGNED MESSAGE----- Microsoft Security Bulletin (MS00-033) - - -------------------------------------- Patch Available for "Frame Domain Verification", "Unauthorized Cookie Access", and "Malformed Component Attribute" Vulnerabilities Originally Posted: May 17, 2000 Summary ======= Microsoft has released a comprehensive patch that eliminates three security vulnerabilities in Microsoft(r) Internet Explorer 4 and 5: - The "Frame Domain Verification" vulnerability, which could allow a malicious web site operator to read, but not change or add, files on the computer of a visiting user. - The "Unauthorized Cookie Access" vulnerability, which could allow a malicious web site operator to access "cookies" belonging to a visiting user. - The "Malformed Component Attribute" vulnerability, which could allow a malicious web site operator to run code of his choice on the computer of a visiting user. Issue ===== The three security vulnerabilities eliminated by this patch are unrelated to each other except by the fact that they all occur in the same .dll. We have packaged them together for customer convenience. The vulnerabilities are: - "Frame Domain Verification" vulnerability. When a web server opens a frame within a window, the IE security model should only allow the parent window to access the data in the frame if they are in the same domain. However, two functions available in IE do not properly perform domain checking, with the result that the parent window could open a frame that contains a file on the local computer, then read it. This could allow a malicious web site operator to view files on the computer of a visiting user. The web site operator would need to know (or guess) the name and location of the file, and could only view file types that can be opened in a browser window. - "Unauthorized Cookie Access" vulnerability. By design, the IE security model restricts cookies so that they can be read only by sites within the originator's domain. However, by using a specially-malformed URL, it is possible for a malicious web site operator to gain access to another site's cookie and read, add or change them. A malicious web site operator would need to entice a visiting user into clicking a link in order to access each cookie, and could not obtain a listing of the cookies available on the visitor's system. Even after recovering a cookie, the type and amount of personal information would depend on the privacy practices followed by the site that placed it there. - "Malformed Component Attribute" vulnerability. The code used to invoke ActiveX components in IE has an unchecked buffer and could be exploited by a malicious web site operator to run code on the computer of a visiting user. The unchecked buffer is only exposed when certain attributes are specified in conjunction with each other. The patch also eliminates a new variant of the previously-addressed WPAD Spoofing vulnerability (http://www.microsoft.com/technet/security/bulletin/ms99-054.asp). Affected Software Versions ========================== - Microsoft Internet Explorer 4.0 - Microsoft Internet Explorer 4.01 - Microsoft Internet Explorer 5.0 - Microsoft Internet Explorer 5.01 Patch Availability ================== - http://www.microsoft.com/windows/ie/download/critical/patch6.htm Note: The patches require IE 4.01 Service Pack 2 or IE 5.01 to install. Customers using versions prior to these may receive a message reading "This update does not need to be installed on this system". This message is incorrect. More information is available in KB article Q262509. Note: Additional security patches are available at the Microsoft Download Center More Information ================ Please see the following references for more information related to this issue. - Frequently Asked Questions: Microsoft Security Bulletin MS00-033, http://www.microsoft.com/technet/security/bulletin/fq00-033.asp - Microsoft Knowledge Base article Q262509 discusses the overall patch and will be available soon. - Microsoft Knowledge Base articles Q251108 and 255676 discuss the "Frame Domain Verification" vulnerability and will be available soon. - Microsoft Knowledge Base article Q258430 discusses the "Unauthorized Cookie Access" vulnerability and will be available soon. - Microsoft Knowledge Base article Q261257 discusses the "Malformed Component Attribute" vulnerability and will be available soon. - Microsoft Knowledge Base (KB) article Q247333, Web Proxy Auto-Discovery "Spoofing" May Change Proxy Settings, http://www.microsoft.com/technet/support/kb.asp?ID=247333 - Microsoft TechNet Security web site, http://www.microsoft.com/technet/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 thanks the following people for working with us to protect customers: - Mead & Company's Andrew Nosenko for reporting the "Frame Domain Verification" issue to us - Marc Slemko for reporting the "Unauthorized Cookie Access" vulnerability to us. - UNYUN, the Shadow Penguin Security Research Group of Japan, for reporting the "Malformed Component Attribute" vulnerability to us. Revisions ========= - May 17, 2000: Bulletin Created. - - ------------------------------------------------------------ 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. Last updated May 17, 2000 (c) 2000 Microsoft Corporation. All rights reserved. Terms of use. - -----BEGIN PGP SIGNATURE----- Version: PGP 6.0.2 iQEVAwUBOSM9No0ZSRQxA/UrAQGTCggAni1/ZkBUGBT1XnI0anqPhY7+cTu0Q1is GjITriIFM8e0gDC9RxYE4Gjh7/AlvSfUZQz3ApxFzi2ltavJULn7vE7bEFNGhj1a uUvEApqJ/xeLreMMNMQx1sz6HN15U4HJjO9Q9If98fdr0UELkFFciVeJXGSDEYCT f/UcZWKxZIQlxG2QgGAqfMSOrYu/FyYfuTOawIPbwQ3s2kKJ8kH477jS+kpkxzoC I29HpQpW/BMDW3HtkX+HWx2Q592X958j7dkxWsGkCgVbbVCjozOLFRLk57awkHrU mvLezVxT4y1l2NV0xIgEXaoiMPzHGO+Voo7xUdQloSIF+ztMWv9Zkw== =EwPj - -----END PGP SIGNATURE----- [****** End Microsoft Bulletin ******] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Microsoft Corporation for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). 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Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ (or http://ciac.llnl.gov -- they're the same machine) Anonymous FTP: ftp.ciac.org (or ciac.llnl.gov -- they're the same machine) Modem access: +1 (925) 423-4753 (28.8K baud) +1 (925) 423-3331 (28.8K baud) PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC) K-035: Backdoor Password in Red Hat Linux Virtual Server Package K-036: Continuing Compromises of DNS Servers K-037: "mstream" Distributed Denial of Service Tool J-043g: Creating Login Banners K-039: Love Letter Worm K-038: Security Holes in FileMaker 5 Web Companion K-040: Netscape Navigator Improperly Validates SSL Sessions K-041: Denial of Service and File Reading Vulnerabilities K-042: Microsoft "Office 2000 UA Control" Vulnerability K-043: Buffer Overrun Vulnerabilities in Kerberos -----BEGIN PGP SIGNATURE----- Version: 4.0 Business Edition iQCVAwUBOSsDQ7nzJzdsy3QZAQFk0wQA0exyZOZu5L9pBC43EIBNlEy90Ztfbckt /ssXz1veJEMKfmxaDfgwYeyGuvIVqUv0cQglBc0vXShUwqhqk5Ggzuwk/EtMeqsO uEJMlTwcz4xwrGT/QdJFidVC0xRor8/lQpyNGG/ZutlNlu6sZzUvAGEGAAz6UDmp /3OjUHskEtw= =F/OH -----END PGP SIGNATURE-----