From ciac@tholia.llnl.gov Mon Aug 3 15:03:18 1998 From: CIAC Mail User To: ciac-bulletin@tholia.llnl.gov Date: Mon, 27 Jul 1998 12:24:22 -0700 (PDT) Subject: CIAC Bulletin I-077: Mime Name Vulnerability in Outlook and Messenger [ For Public Release ] -----BEGIN PGP SIGNED MESSAGE----- __________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ ADVISORY BULLETIN Mime Name Vulnerability in Outlook and Messenger July 27, 1998 20:00 GMT Number I-077 ______________________________________________________________________________ PROBLEM: A buffer overflow vulnerability has been identified in Microsoft Outlook, Outlook Express, and Netscape Messenger (Mail) that allows an e-mail or news message to contain malicious code in a mime header. That code is executed when the header is read by the e-mail/news reader. All of these e-mail/news readers are widely distributed with popular packages such as Internet Explorer, Windows 98, Windows 97, Office 97, and Netscape Communicator. PLATFORM: Any platform that runs the vulnerable e-mail/news readers: Windows 95, Windows 98, Windows NT, Macintosh and Solaris. DAMAGE: If exploited, this vulnerability allows a remote user to run arbitrary code on a users machine with the user's privileges. The remotely executed code could do anything from sending thousands of e-mails in the user's name to formatting the hard drive. SOLUTION: Apply patches from Microsoft and Netscape. ______________________________________________________________________________ VULNERABILITY Risk is high. While we have not yet heard of anyone exploiting ASSESSMENT: this vulnerability for malicious purposes, the ease with which it can be exploited, the wide distribution of vulnerable readers, and the potential for damage makes it a very serious problem. ______________________________________________________________________________ Mime Name Vulnerability in Outlook and Messenger CIAC has received information about a vulnerability in the Microsoft and Netscape e-mail/news products: Outlook, Outlook Express, and Messenger (Mail). These e-mail/news programs improperly handle the mime name tags used to identify attachments to e-mail/news messages. An improper name tag can result in a buffer overflow condition when the program processes the attachment. As the reader generally processes the attachments when the user reads the message, the buffer overflow condition can be initiated, by simply reading the e-mail/news message. The buffer overflow condition can then be exploited to run any arbitrary code contained in the attachment. The code runs with the user's permissions to do anything the user can do such as re-send the e-mail to the users mailing list, change files, or format the hard drive. While at first glance this appears to the Good_Times hoax come to life (see http://ciac.llnl.gov/ciac/CIACHoaxes.html#goodtimes) this is not really the case. Good_Times was supposed to run itself on any system that downloaded and read the Good_Times message. This mime name vulnerability is caused by improperly handled mime headers in a few versions of some very popular e- mail/news readers. By replacing the vulnerable readers with properly patched versions, this vulnerability is eliminated. BACKGROUND ========== The Multipurpose Internet Mail Extensions or MIME is a protocol for sending non-ASCII text or multi-part documents as part of e-mail or news message. Users of the readers rarely see the mime headers since they are stripped out of the message as it is downloaded onto the user's machine. The mime headers tell the reader where the different parts of the message begin and end, what type of data is contained in the message part, what encoding is used to convert the message, what the name of the file is that was attached as a message part, and other information necessary for the successful transmission of the data. In the vulnerable readers, the headers are read into memory without checking their length. When the length of the header is longer than the buffer in memory where the reader tries to store it, data in the header beyond the length of the buffer overwrites other code and data in memory. This overwriting is the classic "buffer overflow" condition. If the overwritten piece of memory is part of the running program, the code from the header in the overwritten part is executed in place of the program's code. ASSESSMENT ========== As of the release date of this advisory, we have not heard of anyone exploiting this vulnerability but we believe it to be extremely serious. Users should take immediate action to patch vulnerable systems. We base this assessment on the ease with which the vulnerability can be exploited, the widespread use of the vulnerable e-mail/news readers, and the potential for doing serious damage to a computer. An additional, serious, long-term problem is the fact that these e-mail/news readers are automatically installed on many systems along with web browsers, office applications and operating systems. For example, Windows 98 comes preinstalled on many new systems and contains one of the vulnerable readers. As the installations are usually done from a CD-ROM, reinstalling a system in the future for any reason reinstalls the vulnerable readers. Users must insure that if they reinstall systems that they then replace the vulnerable readers with appropriately patched versions. VULNERABLE APPLICATIONS ======================= Vulnerabilities in the following applications have been confirmed by the manufacturers: Outlook Express v4.72.2106.4 and v4.72.3110.1 Outlook '98 Netscape Messenger (Mail) v4.05, or 4.5b1 Earlier versions of these applications are also likely to be vulnerable. The current version of Eudora does not appear to be vulnerable. Older e-mail readers that do not handle mime attachments are not vulnerable. PATCHES ======= Information is available from Microsoft at: http://www.microsoft.com/ie/security/oelong.htm Patched versions of Outlook and Outlook Express are available from Microsoft at the URL: Outlook 98 http://support.microsoft.com/support/msfe Request the patch OLMIME from Microsoft Support Outlook Express First update to Internet Explorer 4.01 at: http://www.Microsoft.com/ie Then obtain the patch from: http://www.microsoft.com/ie/security/oelong.htm Patches for Macintosh and Solaris versions of Outlook Express will be available soon at: http://www.Microsoft.com/security Version 4.06 of Netscape Communicator is due out around August 7 and will contain a patched version of the e-mail reader. Patches will be available through their Smart Update web page: http://home.netscape.com/download/su1.html ______________________________________________________________________________ A special thanks goes to Ari Takanen and Marko Laakso of the University of Oulu in Finland and Russ Cooper the Owner/Moderator of the NTBugtraq mailing list for finding and verifying this vulnerability. ______________________________________________________________________________ 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. 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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. 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LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC) I-067: AutoStart 9805 Macintosh Worm Virus I-068: File Access Issue With Internet Information Server I-069: Buffer overflows in some POP servers I-070: Distributed DoS Attack Against NIS/NIS+ Networks I-071: OpenVMS loginout Vulnerability I-072: SunOS Solaris Vulnerabilities (libnsl, SUNWadmap) I-073: multiscan ('mscan') Tool I-074: Buffer Overflow in Some Implementations of IMAP Servers I-075: Microsoft Office 98 Security Vulnerability I-076: SGI IRIX ioconfig(1M) and disk_bandwidth(1M) Vulnerability -----BEGIN PGP SIGNATURE----- Version: 4.0 Business Edition iQCVAwUBNbzLSLnzJzdsy3QZAQFf2gQAli0YHsRhVwyIM/uAHnF/4I/gfN2rrJ52 w+5xsToSqwktDwatMlI+M+4q3j9Q3xoPd4IzI/KA3ynd0yaIxz4Y0kbeVAdvlQCm KagIofKEUXF6P/PnaVX3xMUS3Jxt/ZJgF7hEnBBzXNhCi/3llz6YLf3JH6KPV1CL 3zeTbiORrMk= =uDaP -----END PGP SIGNATURE-----