__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft Outlook Express Unchecked Buffer in S/MIME Vulnerability [Microsoft Security Bulletin MS02-058] October 11, 2002 14:00 GMT Number N-007 ______________________________________________________________________________ PROBLEM: To allow for verification of the authenticity of mail messages, Microsoft Outlook Express supports digital signing of messages through S/MIME. A buffer overrun vulnerability lies in the code that generates the warning message when a particular error condition associated with digital signatures occurs. AFFECTED Microsoft Outlook Express 6.0 SOFTWARE: Microsoft Outlook Express 5.5 DAMAGE: By sending a specially crafted e-mail that contains a malformed S/MIME certificate: (1) an attacker could cause the mail client to run code of his/her choice limited only by the e-mail recipient's permissions on the machine. (2) an attacker could cause the mail client to fail by overrunning the buffer with random data. SOLUTION: Apply available patch. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. The vulnerability only affects Microsoft ASSESSMENT: Outlook Express, not Microsoft Outlook. An attacker could run code of his/her choice which includes reformatting the hard drive. Simply opening the e-mail, or viewing it through Preview Mode, could allow the attacker to exploit the vulnerability. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-007.shtml ORIGINAL BULLETIN: http://www.microsoft.com/technet/treeview/default.asp?url= /technet/security/bulletin/MS02-058.asp PATCHES: http://www.microsoft.com/windows/ie/downloads/critical/ q328676/default.asp ______________________________________________________________________________ [***** Start Microsoft Security Bulletin MS02-058 *****] Microsoft Security Bulletin MS02-058 Unchecked Buffer in Outlook Express S/MIME Parsing Could Enable System Compromise (Q328676) Originally posted: October 10, 2002 Summary Who should read this bulletin: Customers using Microsoft® Outlook Express Impact of vulnerability: Run code of attackers choice. Maximum Severity Rating: Critical Recommendation: Customers using Outlook Express should apply the patch Affected Software: Microsoft Outlook Express 6.0 Microsoft Outlook Express 5.5 Note: Microsoft Outlook is a different product than Microsoft Outlook Express, and is not affected by the vulnerability. Technical details Technical description: To allow for verification of the authenticity of mail messages, Microsoft Outlook Express supports digital signing of messages through S/MIME. A buffer overrun vulnerability lies in the code that generates the warning message when a particular error condition associated with digital signatures occurs. By creating a digitally signed email and editing it to introduce specific data, then sending it to another user, an attacker could cause either of two effects to occur if the recipient opened or previewed it. In the less serious case, the attacker could cause the mail client to fail. If this happened, the recipient could resume normal operation by restarting the mail client and deleting the offending mail. In the more serious case, the attacker could cause the mail client to run code of their choice on the user’s machine. Such code could take any desired action, limited only by the permissions of the recipient on the machine. This vulnerability could only affect messages that are signed using S/MIME and sent to an Outlook Express user. Users of Microsoft Outlook products are not affected by this vulnerability. Mitigating factors: Microsoft Outlook is not affected by this vulnerability. Outlook Express runs in the context of the user. Exploiting this vulnerability would in the worst case scenario allow an attacker to run arbitrary code in the context of the users’ privileges only. Any restrictions on the users’ account would apply to the attackers code. Severity Rating: Internet Servers Intranet Servers Client Systems Outlook Express 6.0 Low Low Critical Outlook Express 5.5 Low Low 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. Vulnerability identifier: CAN-2002-1179 Tested Versions: Microsoft tested Outlook Express 5.5 and 6.0 to assess whether they are affected by these vulnerabilities. Previous versions are no longer supported, and may or may not be affected by these vulnerabilities. Patch availability Download locations for this patch Microsoft Outlook Express: http://www.microsoft.com/windows/ie/downloads/critical/q328676/default.asp Additional information about this patch Installation platforms: The patch for Outlook Express 6.0 can be applied to systems running Outlook Express 6.0 Gold. The patch for Outlook Express 5.5 can be applied to systems running Outlook Express 5.5 Service Pack 2. Inclusion in future service packs: The fix for this issue is included in Outlook Express 6.0 Service Pack 1 (which is available in Internet Explorer 6.0 Service Pack 1 or as part of Windows XP Service Pack 1). The fix for this issue will be included in any future service packs for Outlook Express 5.5. Reboot needed: No Patch can be uninstalled: No Superseded patches: None. Verifying patch installation: Outlook Express 6.0 To verify that the patch has been installed on the machine, open Internet Explorer, select Help, then select About Internet Explorer and confirm that Q328676 is listed in the Update Versions field. Alternatively, from Outlook Express select Help, then select About Outlook Express and confirm that the msoe.dll matches the version called out in Q328676. To verify the individual files, use the patch manifest provided in Knowledge Base article Q328676. Outlook Express 5.5 Service Pack 2 To verify that the patch has been installed on the machine, open IE, select Help, then select About Internet Explorer and confirm that Q328389 is listed in the Update Versions field. Alternatively, from Outlook Express select Help, then select About Outlook Express and confirm that the msoe.dll matches the version called out in Q328389. To verify the individual files, use the patch manifest provided in Knowledge Base article Q328389. Caveats: Under a very unusual set of conditions, it could be possible to inadvertently remove the patch. Specifically, if the patch is installed on a system, and the user subsequently installs and uninstalls Windows XP Service Pack 1, the effect will be to remove not only Service Pack 1, but the patch as well. Similarly, installing and the uninstalling Internet Explorer 6.0 Service Pack 1 will remove the patch, if it’s previously been installed. In either scenario, the patch should be separately re-applied after uninstalling the service pack. 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: Acknowledgments Microsoft thanks Noam Rathaus of Beyond Security Ltd. (http://www.beyondsecurity.com) for reporting this issue to us and working with us to protect customers. Support: Microsoft Knowledge Base article Q328676 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 (October 10, 2002): Bulletin Created. [***** End Microsoft Security Bulletin MS02-058 *****] _______________________________________________________________________________ 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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