****************************************************************************** ------ ----- ----- --- ----- | ----- ---- | | | | | |--- | | | | | | | | | |-- | | | | |-- | | | | | | | | \ | | ----- ---- ----- ----- | \ ----- A D V I S O R Y FA-98.12 ****************************************************************************** Topic: Denial of service attacks targeting Windows 95/NT machines Source: CERT/CC Creation Date: March 4, 1998 Last Updated: To aid in the wide distribution of essential security information, FedCIRC is forwarding the following information from CERT/CC Summary CS-98.02 (Special Edition). FedCIRC urges you to act on this information as soon as possible. If you have any questions, please contact FedCIRC: Telephone: +1 888 282 0870 Email: fedcirc@fedcirc.gov =======================FORWARDED TEXT STARTS HERE============================ -----BEGIN PGP SIGNED MESSAGE----- - --------------------------------------------------------------------------- CERT* Summary CS-98.02 - SPECIAL EDITION March 4, 1998 This special edition of the CERT Summary reports denial of service attacks targeting a vulnerability in the Microsoft TCP/IP stack. Past CERT Summaries are available from ftp://ftp.cert.org/pub/cert_summaries/ - --------------------------------------------------------------------------- Denial of service attacks targeting Windows 95/NT machines - ---------------------------------------------------------- This special edition of the CERT Summary reports denial of service attacks targeting a vulnerability in the Microsoft TCP/IP stack. We have received reports from a number of sites and incident response teams indicating that a large number of machines were affected. The attacks involve sending a pair of malformed IP fragments which are reassembled into an invalid UDP datagram. The invalid UDP datagram causes the target machine to go into an unstable state. Once in an unstable state, the target machine either halts or crashes. We have received reports that some machines crashed with a blue screen while others rebooted. Attack tools known by such names as NewTear, Bonk, and Boink have been previously used to exploit this vulnerability against individual hosts; however, in this instance, the attacker used a modified tool to automatically attack a large number of hosts. The solution to protect Windows 95 and NT machines from this attack is to apply the appropriate Microsoft patch. The Microsoft patch, as well as more information about the vulnerability, can be found in the January 1998 Microsoft Market Bulletin entitled, "New Teardrop-like TCP/IP Denial of Service Program" available from: http://www.microsoft.com/security/newtear2.htm Although the first instance of this attack, which started March 2, 1998 appears to be over, keep in mind that the tools to launch this attack are now available and we expect to see more incidents of this type. - --------------------------------------------------------------------------- How to Contact the CERT Coordination Center Email cert@cert.org Phone +1 412-268-7090 (24-hour hotline) CERT personnel answer on business days 8:30-5:00 p.m. EST (GMT-5)/EDT(GMT-4), and are on call for emergencies during other hours. Fax +1 412-268-6989 Postal address CERT Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh PA 15213-3890 USA To be added to our mailing list for CERT advisories and bulletins, send your email address to cert-advisory-request@cert.org In the subject line, type SUBSCRIBE your-email-address CERT advisories and bulletins are posted on the USENET news group comp.security.announce CERT publications, information about FIRST representatives, and other security-related information are available for anonymous FTP from http://www.cert.org/ ftp://ftp.cert.org/pub/ If you wish to send sensitive incident or vulnerability information to CERT staff by electronic mail, we strongly advise you to encrypt your message. We can support a shared DES key or PGP. Contact the CERT staff for more information. Location of CERT PGP key ftp://ftp.cert.org/pub/CERT_PGP.key - --------------------------------------------------------------------------- Copyright 1998 Carnegie Mellon University. Conditions for use, disclaimers, and sponsorship information can be found in http://www.cert.org/legal_stuff.html and ftp://ftp.cert.org/pub/legal_stuff . If you do not have FTP or web access, send mail to cert@cert.org with "copyright" in the subject line. * CERT is registered in the U.S. Patent and Trademark Office. -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBNP2ZWnVP+x0t4w7BAQEqhQP/QDajvNSm4GFYeQlV9IZsgGCce6Q299wq zaJfeINKgKgsrJNr0aZPwlQh/Px/yfxsR1XmDj2uUEC/h3vN+kkfMT10BYwD9LPk iKJZ1HqXNfydksuaVdjsAaCUwTYLW7guNPrkufDB3dvo05CODTx4PjP/4a/l3vbj 5f7rb+kwSQQ= =gjWg -----END PGP SIGNATURE----- ========================FORWARDED TEXT ENDS HERE============================= The National Institute of Standards and Technology (NIST) has established a Federal Computer Incident response Capability (FedCIRC) to assist federal civilians agencies in their incident handling efforts by providing proactive and reactive computer security related services. FedCIRC is a partnership among NIST, the Computer Incident Advisory Capability (CIAC), and the CERT* Coordination Center (CERT/CC). If you believe that your system has been compromised, please contact FedCIRC: Telephone: +1 888 282 0870 Email: fedcirc@fedcirc.gov Web Server: http://www.fedcirc.gov/ * Registered in U.S. Patent and Trademark Office The CERT Coordination Center is part of the Software Engineering Institute. The Software Engineering Institute is sponsored by the U.S. Department of Defense. 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. 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.