__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Buffer Overrun in Microsoft HTML Converter Could Allow Code Execution [Microsoft Security Bulletin MS03-023] July 10, 2003 17:00 GMT Number N-114 ______________________________________________________________________________ PROBLEM: There is a flaw in the way the HTML converter for Microsoft Windows handles a conversion request during a cut-and-paste operation. A specially crafted request to the HTML converter could cause the converter to fail in such a way that it could execute code in the context of the currently logged-in user. SOFTWARE: * Microsoft Windows 98 * Microsoft Windows 98 Second Edition * Microsoft Windows Me * Microsoft Windows NT 4.0 Server * Microsoft Windows NT 4.0 Terminal Server Edition * Microsoft Windows 2000 * Microsoft Windows XP * Microsoft Windows Server 2003 DAMAGE: Because this functionality is used by Internet Explorer, an attacker could craft a specially formed Web page or HTML e-mail that would cause the HTML converter to run arbitrary code on a user's system. SOLUTION: Apply patches as stated in Microsoft's security bulletin. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. To exploit this vulnerability, the attacker ASSESSMENT: would have to create a specially-formed HTML e-mail and send it to the user. The attacker would have to host a Web site that contained a Web page used to exploit this vulnerability, and persuade a user to visit that site. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-114.shtml ORIGINAL BULLETIN: http://www.microsoft.com/technet/treeview/ default.asp?url=/technet/security/bulletin/MS03-023.asp ______________________________________________________________________________ [***** Start Microsoft Security Bulletin MS03-023 *****] Microsoft Security Bulletin MS03-023 Buffer Overrun In HTML Converter Could Allow Code Execution (823559) Originally posted: July 9, 2003 Summary Who should read this bulletin: Users running Microsoft ® Windows ® Impact of vulnerability: Run code of attacker’s choice Maximum Severity Rating: Critical Recommendation: Systems administrators should apply the patch immediately Affected Software: * Microsoft Windows 98 * Microsoft Windows 98 Second Edition * Microsoft Windows Me * Microsoft Windows NT 4.0 Server * Microsoft Windows NT 4.0 Terminal Server Edition * Microsoft Windows 2000 * Microsoft Windows XP * Microsoft Windows Server 2003 Technical details Technical description: All versions of Microsoft Windows contain support for file conversion within the operating system. This functionality allows users of Microsoft Windows to convert file formats from one to another. In particular, Microsoft Windows contains support for HTML conversion within the operating system. This functionality allows users to view, import, or save files as HTML. There is a flaw in the way the HTML converter for Microsoft Windows handles a conversion request during a cut-and-paste operation. This flaw causes a security vulnerability to exist. A specially crafted request to the HTML converter could cause the converter to fail in such a way that it could execute code in the context of the currently logged-in user. Because this functionality is used by Internet Explorer, an attacker could craft a specially formed Web page or HTML e-mail that would cause the HTML converter to run arbitrary code on a user's system. A user visiting an attacker’s Web site could allow the attacker to exploit the vulnerability without any other user action. To exploit this vulnerability, the attacker would have to create a specially-formed HTML e-mail and send it to the user. Alternatively, an attacker would have to host a malicious Web site that contains a Web page designed to exploit this vulnerability. The attacker would then have to persuade a user to visit that site. Mitigating factors: * By default, Internet Explorer on Windows Server 2003 runs in Enhanced Security Configuration. This default configuration of Internet Explorer blocks automatic exploitation of this attack. If Internet Explorer Enhanced Security Configuration has been disabled, the protections put in place that prevent this vulnerability from being automatically exploited would be removed. * In the Web-based attack scenario, the attacker would have to host a Web site that contained a Web page used to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site outside the HTML e-mail vector. Instead, the attacker would need to lure them there, typically by getting them to click a link that would take them to the attacker's site. * Exploiting the vulnerability would allow the attacker only the same privileges as the user. Users whose accounts are configured to have few privileges on the system would be at less risk than ones who operate with administrative privileges. Severity Rating: Windows 98 Critical Windows 98 Second Edition Critical Windows Me Critical Windows NT 4.0 Server Critical Windows NT 4.0 Terminal Server Edition Critical Windows 2000 Critical Windows XP Critical Windows Server 2003 Moderate 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. Vulnerability identifier: CAN-2003-0469 Tested Versions: Microsoft tested Windows 98, Windows 98 Second Edition, Windows Me, Windows NT 4.0 Server, Windows NT 4.0 Terminal Services Edition, Windows 2000, Windows XP and Windows Server 2003 to assess whether they are affected by this vulnerability. Previous versions are no longer supported, and may or may not be affected by these vulnerabilities. Patch availability Download locations for this patch * Windows NT 4.0 Server * Windows NT 4.0 Terminal Server Edition * Windows 2000 * Windows XP 32 bit Edition * Windows XP 64 bit Edition * Windows Server 2003 32 bit Edition * Windows Server 2003 64 bit Edition Additional information about this patch Installation platforms: * The Window 98 patch can be installed on systems running Windows 98 Gold. * The Window 98 Second Edition patch can be installed on systems running Windows 98SE Gold. * The Windows Me patch can be installed on systems running Windows Me Gold. * The Windows NT 4.0 patch can be installed on systems running Service Pack 6a. * The Windows NT 4.0, Terminal Server Edition patch can be installed on systems running Windows NT 4.0, Terminal Server Edition Service Pack 6. * The Windows 2000 patch can be installed on systems running Windows 2000 Service Pack 3, or Service Pack 4. * The patch for Windows XP can be installed on systems running Windows XP Gold or Service Pack 1. * The patch for Windows Server 2003 can be installed on systems running Windows Server 2003 Gold. Inclusion in future service packs: The fix for this issue will be included in Windows 2000 Service Pack 5, Windows XP Service Pack 2, and Windows Server 2003 Service Pack 1. Reboot needed: No. Patch can be uninstalled: Yes. Superseded patches: None. Verifying patch installation: * Windows 98, Windows 98 Second Edition, Windows Me: To verify that the patch has been installed on the machine consult the file manifest in Knowledge Base article 823559. * Windows NT 4.0: To verify that the patch has been installed on the machine, confirm that all files listed in the file manifest in Knowledge Base article 823559 are present on the system. * Windows NT 4.0 Terminal Server Edition: To verify that the patch has been installed on the machine, confirm that all files listed in the file manifest in Knowledge Base article 823559 are present on the system. * Windows 2000: To verify that the patch has been installed on the machine, confirm that the following registry key has been created on the machine: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows 2000\SP5\KB823559. To verify the individual files, use the date/time and version information provided in the file manifest in Knowledge Base article 823559 are present on the system. * Windows XP: To verify that the patch has been installed on the machine, confirm that the following registry key has been created on the machine: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows XP\SP2\KB823559. To verify the individual files, use the date/time and version information provided in the file manifest in Knowledge Base article 823559 are present on the system. * Windows Server 2003: To verify that the patch has been installed on the machine, confirm that the following registry key has been created on the machine: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Window Server 2003\SP1\KB823559. To verify the individual files, use the date/time and version information provided in the file manifest in Knowledge Base article 823559 are present on the system. 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 Other information: Support: * Microsoft Knowledge Base article 823559 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 (July 9, 2003): Bulletin Created. [***** End Microsoft Security Bulletin MS03-023 *****] _______________________________________________________________________________ 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). 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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