************************************************************************** Security Bulletin 9807 DISA Defense Communications System March 4, 1998 Published by: DISN Security Coordination Center (SCC@NIC.MIL) 1-(800) 365-3642 DEFENSE INFORMATION SYSTEM NETWORK SECURITY BULLETIN The DISN SECURITY BULLETIN is distributed by the DISN SCC (Security Coordination Center) under DISA contract as a means of communicating information on network and host security exposures, fixes, and concerns to security and management personnel at DISN facilities. Back issues may be obtained via FTP from NIC.MIL [207.132.116.5] using login= "anonymous" and password="guest". The bulletin pathname is scc/sec-yynn (where "yy" is the year the bulletin is issued and "nn" is a bulletin number, e.g. scc/sec-9705.txt). These are also available at our WWW site, http://nic.mil. ************************************************************************** + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + ! ! ! The following important advisory was issued by the Computer ! ! Emergency Response Team (CERT) and is being relayed unedited ! ! via the Defense Information Systems Agency's Security ! ! Coordination Center distribution system as a means of ! ! providing DISN subscribers with useful security information. ! ! ! + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + ============================================================================= -----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----- **************************************************************************** * * * The point of contact for NIPRNET security-related incidents is the * * ASSIST: * * * * E-mail address: ASSIST@ASSIST.MIL * * * * Telephone: 1-(800)-357-4231 (24 hours/day) * * * * You may also contact the Security Coordination Center (SCC) at the * * NIC: * * * * E-mail address: SCC@NIC.MIL * * * * Telephone: 1-(800)-365-3642 * * * * NIC Help Desk personnel are available from 7:00 a.m.-7:00 p.m. EST, * * Monday through Friday except on federal holidays. * * * **************************************************************************** PLEASE NOTE: Some users outside of the DOD computing communities may receive DISN Security Bulletins. If you are not part of the DOD community, please contact your agency's incident response team to report incidents. Your agency's team will coordinate with DOD. 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 by sending email to docserver@first.org with an empty subject line and a message body containing the line: send first-contacts. This document was prepared as an service to the DOD community. Neither the United States Government nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, 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. The opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government, and shall not be used for advertising or product endorsement purposes.