__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft Cumulative Patch for Internet Explorer [Microsoft Security Bulletin MS02-023] May 23, 2002 21:00 GMT Number M-082 ______________________________________________________________________________ PROBLEM: There are six new vulnerabilities in Internet Explorer. * Cross-Site Scripting in Local HTML Resource * Local Information Disclosure through HTML object * Script within Cookies Reading Cookies * Zone Spoofing through Malformed Web Page * Two "Content Disposition" Variants A description of each vulnerability, if exploitable, is provided within Microsoft's Security bulletin. PLATFORM: Internet Explorer 5.01, Internet Explorer 5.5, and Internet Explorer 6.0. DAMAGE: The aggregate of severity is based on the types of systems affected by the vulnerability, their deployment patterns, and the effect that exploiting the vulnerability would have on them. SOLUTION: Apply appropriate patch for appropriate Internet Explorer version as prescribed by Microsoft. ______________________________________________________________________________ VULNERABILITY The risk is HIGH. The most serious vulnerability may allow an ASSESSMENT: attacker to run code of choice. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/m-082.shtml ORIGINAL BULLETIN: http://www.microsoft.com/technet/treeview/ default.asp?url=/technet/security/ bulletin/MS02-023.asp ______________________________________________________________________________ [***** Start Microsoft Security Bulletin MS02-023 *****] Microsoft Security Bulletin MS02-023 15 May 2002 Cumulative Patch for Internet Explorer (Q321232) Originally posted: May 15, 2002 Summary Who should read this bulletin: Customers using Microsoft® Internet Explorer Impact of vulnerability: Six new vulnerabilities, the most serious of which could allow code of attacker's choice to run. Maximum Severity Rating: Critical Recommendation: Consumers using the affected versions of IE should install the patch immediately. Affected Software: Microsoft Internet Explorer 5.01 Microsoft Internet Explorer 5.5 Microsoft Internet Explorer 6.0 Technical details Technical description: This is a cumulative patch that includes the functionality of all previously released patches for IE 5.01, 5.5 and 6.0. In addition, it eliminates the following six newly discovered vulnerabilities: * A cross-site scripting vulnerability in a Local HTML Resource. IE ships with several files that contain HTML on the local file system to provide functionality. One of these files contains a cross-site scripting vulnerability that could allow a script to execute as if it were run by the user herself, causing it to run in the local computer zone. An attacker could craft a web page that exploits this vulnerability and then either host that page on a web server or send it as HTML email. When the web page was viewed and the attacker's script run, the attacker's script would be injected into the local resource, where it would run in the Local Computer zone, allowing it to run with fewer restrictions than it would in the Internet Zone. * An information disclosure vulnerability related to the use of am HTML object provides that support for Cascading Style Sheets that could allow an attacker to read, but not add, delete or change, data on the local system. An attacker could craft a web page that exploits this vulnerability and then either host that page on a web server or send it as HTML email. When the page was viewed, the element would be invoked. Successfully exploiting this vulnerability, however, requires exact knowledge of the location of the intended file to be read on the user's system. Further, it requires that the intended file contain a single, parcicular ASCII character. * An information disclosure vulnerability related to the handling of script within cookies that could allow one site to read the cookies of another. An attacker could build a special cookie containing script and then construct a web page that would deliver that cookie to the user's system and invoke it. He could then send that web page as mail or post it on a server. When the page executed and invoked the script in the cookie, it could potentially read or alter the cookies of another site. Successfully exploiting this, however, would require that the attacker know the exact name of the cookie as stored on the file system to be read successfully. * A zone spoofing vulnerability that could allow a web page to be incorrectly reckoned to be in the Intranet zone or, in some very rare cases, in the Trusted Sites zone. An attacker could construct a web page that exploits this vulnerability and attempt to entice the user to visit the web page. If the attack were successful, the page would be run with fewer security restrictions than is appropriate. * Two variants of the "Content Disposition" vulnerability discussed in Microsoft Security Bulletin MS01-058 affecting how IE handles downloads when a downloadable file's Content-Disposition and Content-Type headers are intentionally malformed. In such a case, it is possible for IE to believe that a file is a type safe for automatic handling, when in fact it is executable content. An attacker could seek to exploit this vulnerability by constructing a specially malformed web page and posting a malformed executable file. He could then post the web page or mail it to the intended target. These two new variants differ from the original vulnerability in that they for a system to be vulnerable, it must have present an application present that, when it is erroneously passed the malformed content, chooses to hand it back to the operating system rather than immediately raise an error. A successful attack, therefore, would require that the attacker know that the intended victim has one of these applications present on their system. Finally, it introduces a behavior change to the Restricted Sites zone. Specifically, it disables frames in the Restricted Sites zone. Since the Outlook Express 6.0, Outlook 98 and Outlook 2000 with the Outlook Email Security Update and Outlook 2002 all read email in the Restricted Sites zone by default, this enhancement means that those products now effectively disable frames in HTML email by default. This new behavior makes it impossible for an HTML email to automatically open a new window or to launch the download of an executable. Mitigating factors: Cross-Site Scripting in Local HTML Resource: * Outlook 98 and 2000 (after installing the Outlook Email Security Update), Outlook 2002, and Outlook Express 6 all open HTML mail in the Restricted Sites Zone. As a result, customers using these products would not be at risk from automated email-borne attacks. However, these customers can still be attacked if they choose to click on a hyperlink in a malicious HTML email. * Customers using Outlook 2002 SP1 who have enabled the "Read as Plain Text" feature would be immune from the HTML email attack. This is because this feature disables all HTML elements, including scripting, from mail when it is displayed. * Any limitations on the rights of the user's account would also limit the actions of the attacker's script. * Customers who exercise caution in what web sites they visit or who place unknown or untrusted sites in the Restricted Sites zone can potentially protect themselves from attempts to exploit this issue on the web. Local Information Disclosure through HTML Object: * It can only be used to read information. It cannot add, change or delete any information. * The attacker would need to know the exact name and location on the system of any file they attempted to read. * Only files that contained a particular, individual ASCII character could be read. If this single character is not present, the attempt to read the file would fail. * Outlook 98 and 2000 (after installing the Outlook Email Security Update), Outlook 2002, and Outlook Express 6 all open HTML mail in the Restricted Sites Zone. As a result, customers using these products would not be at risk from automated email-borne attacks. However, these customers can still be attacked if they choose to click on a hyperlink in a malicious HTML email. * Customers using Outlook 2002 SP1 who have enabled the "Read as Plain Text" feature would be immune from the HTML email attack. This is because this feature disables all HTML elements, including scripting, from mail when it is displayed. Script within Cookies Reading Cookies: * The specific information an attacker could access would depend on what information a site has chosen to store in its cookies. Best practices strongly recommend against storing sensitive information in cookies. * Mounting a successful attack requires that the attacker know the exact name and location of the target cookie. This vulnerability provides no means for an attacker to acquire that information. * Outlook 98 and 2000 (after installing the Outlook Email Security Update), Outlook 2002, and Outlook Express 6 all open HTML mail in the Restricted Sites Zone. As a result, customers using these products would not be at risk from automated email-borne attacks. However, these customers can still be attacked if they choose to click on a hyperlink in a malicious HTML email. * Customers using Outlook 2002 SP1 who have enabled the "Read as Plain Text" feature would be immune from the HTML email attack. This is because this feature disables all HTML elements, including scripting, from mail when it is displayed. Zone Spoofing through Malformed Web Page: * A successful attack would require NetBIOS connectivity between the user and the attacker's site. Any filtering of NetBIOS, such as that found by ISP's or at the firewall perimeter, would thwart attempts to exploit this vulnerability. * Any attempt to render a web site in the Trusted Sites zone would require very specific knowledge of custom configuration made by the user. This aspect of the vulnerability is not exploitable by default, nor does the vulnerability give the means to acquire the necessary information for that attack. New Variants of the "Content Disposition" Vulnerability: * Any successful attempt to exploit this vulnerability requires that the attacker know that the intended target have specific versions of specific applications on their system. The vulnerability gives no means for an attacker to know what applications or versions are present on the system. * Any attempt to exploit the vulnerability requires that the attacker host a malicious executable on a server accessible to the intended victim. If the hosting server is unreachable for any reason, such as DNS blocking or the server being taken down, the attack would fail. Severity Rating: Cross-Site Scripting in Local HTML Resource: Internet Servers Intranet Servers Client Systems ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Internet Explorer 5.01 None None None Internet Explorer 5.5 None None None Internet Explorer 6.0 Moderate Moderate Critical ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Local Information Disclosure through HTML Object: Internet Servers Intranet Servers Client Systems ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Internet Explorer 5.01 Moderate Moderate Critical Internet Explorer 5.5 Moderate Moderate Critical Internet Explorer 6.0 Moderate Moderate Critical ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Script within Cookies Reading Cookies: Internet Servers Intranet Servers Client Systems ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Internet Explorer 5.01 None None None Internet Explorer 5.5 Moderate Moderate Critical Internet Explorer 6.0 Moderate Moderate Critical ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Zone Spoofing through Malformed Web Page: Internet Servers Intranet Servers Client Systems ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Internet Explorer 5.01 Low Low Low Internet Explorer 5.5 Low Low Low Internet Explorer 6.0 Low Low Low ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ New Variants of the "Content Disposition" Vulnerability: Internet Servers Intranet Servers Client Systems ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Internet Explorer 5.01 Moderate Moderate Moderate Internet Explorer 5.5 None None None Internet Explorer 6.0 Moderate Moderate Moderate ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Aggregate severity of all vulnerabilities eliminated by patch: Internet Servers Intranet Servers Client Systems ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Internet Explorer 5.01 Critical Critical Critical Internet Explorer 5.5 Critical Critical Critical Internet Explorer 6.0 Critical Critical Critical ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ The above assessment is based on the types of systems affected by the vulnerability, their typical deployment patterns, and the effect that exploiting the vulnerability would have on them. The personal information disclosure vulnerabilities are most likely to affect client systems, based on usage patters. The variants of the "Content Disposition" vulnerability require knowledge of the software installed on a system by the user. The Zone Spoofing vulnerability requires NetBIOS access, which is commonly blocked at the perimeter firewall and by ISP's. The aggregate severity includes the severity of vulnerabilities announced in previously released security bulletins. Vulnerability identifiers: * Cross-Site Scripting in Local HTML Resource: CAN-2002-0189 * Local Information Disclosure through HTML object: CAN-2002-0191 * Script within Cookies Reading Cookies: CAN-2002-0192 * Zone Spoofing through Malformed Web Page: CAN-2002-0190 * "Content Disposition" Variants: CAN-2002-0193, CAN-2002-0188 Tested Versions: The following table indicates which of the currently supported versions of Internet Explorer are affected by the vulnerabilities. Versions of IE prior to 5.01 Service Pack 2 are no longer eligible for hotfix support. IE 5.01 SP2 is supported only via Windows® 2000 Service Packs and Security Roll-up Packages and on Windows NT® 4.0. IE 5.01 SP2 IE 5.5 SP1 IE 5.5 SP2 IE 6.0 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Cross-Site Scripting in Local HTML Resource (CVE-CAN-2002-0189) No No No Yes Local Information Disclosure through HTML object (CAN-2002-0191) Yes Yes Yes Yes Script within Cookies Reading Cookies: (CVE-CAN-2002-0192) No Yes Yes Yes Zone Spoofing through Malformed Web Page (CVE-CAN-2002-0190) Yes Yes Yes Yes New Variants of the "Content Disposition" Vulnerability (CAN-2002-0193 and CAN-2002-0188) Yes No No Yes +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Patch availability Download locations for this patch * http://www.microsoft.com/windows/ie/downloads/critical/Q321232/default.asp Additional information about this patch Installation platforms: * The IE 5.01 patch can be applied to Windows 2000 Systems with Service Pack 2 or Windows NT 4.0 systems with Service Pack 6a. * The IE 5.5 patch can be installed on systems running IE 5.5 Service Pack 1 or Service Pack 2. * The IE 6.0 patch can be installed on system running IE 6.0 Gold. Inclusion in future service packs: * The fixes for these issues will be included in IE 6.0 Service Pack 1. * The fixes for the issues affecting IE 5.01 Service Pack 2 will be included in Windows 2000 Service Pack 3. Reboot needed: Yes Superseded patches: * This patch supersedes the one provided in Microsoft Security Bulletin MS02-015, which is itself a cumulative patch. Verifying patch installation: * To verify that the patch has been installed on the machine, open IE, select Help, then select About Internet Explorer and confirm that Q321232 is listed in the Update Versions field. * To verify the individual files, use the patch manifest provided in Knowledge Base article Q321232. Caveats: None Localization: Localized versions of this patch are available at the locations discussed in "Patch Availability" Obtaining other security patches: Patches for other security issues are available from the following locations: * Security patches are available from the Microsoft Download Center, and can be most easily found by doing a keyword search for "security_patch". * Patches for consumer platforms are available from the WindowsUpdate web site * All patches available via WindowsUpdate also are available in a redistributable form from the WindowsUpdate Corporate site. Other information: Acknowledgments Microsoft thanks the following people for working with us to protect customers: * Jani Laatikainen (jani@laatikainen.net) for reporting one of the "Content-Disposition variants. * Yuu Arai of LAC SNS Team (http://www.lac.co.jp/security/) for reporting one of the "Content-Disposition variants. * Cistobal Bielza Lino and Juan Carlos G. Cuartango from Instituto Seguridad Internet (www.instisec.com) for reporting the Zone Spoofing through Malformed Web Page vulnerability. Support: * Microsoft Knowledge Base article Q321232 discusses this issue and will be available approximately 24 hours after the release of this bulletin. Knowledge Base articles can be found on the Microsoft Online Support web site. * Technical support is available from Microsoft Product Support Services. There is no charge for support calls associated with security patches. Security Resources: The Microsoft TechNet Security Web Site provides additional information about security in Microsoft products. Disclaimer: 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. Revisions: * V1.0 (May 15, 2002): Bulletin Created. * V1.1 (May 16, 2002): Bulletin updated to correct erroneous information regarding attack vectors for the Cross-Site Scripting in Local HTML Resource and Script within Cookies Reading Cookies vulnerabilities and the capabilities of locally run scripts. [***** End Microsoft Security Bulletin MS02-023 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Microsoft Corporation for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Center, 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). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org 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. 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