-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =============================================================================== >> CERT-NL, 01-Mar-2000 << >> All CERT-NL information has been moved to http://cert.surfnet.nl. Links << >> to CERT-NL information contained in this advisory are therefore outdated. << >> << >> CERT-NL also has stopped the CERT-CC-Mirror service. Due to this the << >> links to the CERT-CC mirror are obsolete. Visit the CERT-CC site for the << >> complete CERT-CC advisory texts: http://www.cert.org << =============================================================================== =============================================================================== Security Advisory CERT-NL =============================================================================== Author/Source : Gert Meijerink Index : S-98-08 Distribution : World Page : 1 Classification: External Version: 1 Subject : Denial of service attacks & MS TCP/IP stack Date : 05-Mar-98 =============================================================================== By courtesy of CERT/CC we received information about denial of service attacks targeting a vulnerability in the Microsoft TCP/IP stack. CERT-NL recommends application of the provided patches. ============================================================================== - - --------------------------------------------------------------------------- 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. ============================================================================== CERT-NL is the Computer Emergency Response Team for SURFnet customers. SURFnet is the Dutch network for educational, research and related institutes. CERT-NL is a member of the Forum of Incident Response and Security Teams (FIRST). All CERT-NL material is available under: http://cert.surfnet.nl/ In case of computer or network security problems please contact your local CERT/security-team or CERT-NL (if your institute is NOT a SURFnet customer please address the appropriate (local) CERT/security-team). CERT-NL is one/two hour(s) ahead of UTC (GMT) in winter/summer, i.e. UTC+0100 in winter and UTC+0200 in summer (DST). Email: cert-nl@surfnet.nl ATTENDED REGULARLY ALL DAYS Phone: +31 302 305 305 BUSINESS HOURS ONLY Fax: +31 302 305 329 BUSINESS HOURS ONLY Snailmail: SURFnet bv Attn. CERT-NL P.O. Box 19035 NL - 3501 DA UTRECHT The Netherlands NOODGEVALLEN: 06 22 92 35 64 ALTIJD BEREIKBAAR EMERGENCIES : +31 6 22 92 35 64 ATTENDED AT ALL TIMES CERT-NL'S EMERGENCY PHONENUMBER IS ONLY TO BE USED IN CASE OF EMERGENCIES: THE SURFNET HELPDESK OPERATING THE EMERGENCY NUMBER HAS A *FIXED* PROCEDURE FOR DEALING WITH YOUR ALERT AND WILL IN REGULAR CASES RELAY IT TO CERT-NL IN AN APPROPRIATE MANNER. CERT-NL WILL THEN CONTACT YOU. =============================================================================== -----BEGIN PGP SIGNATURE----- Version: PGP 6.5.1i iQA/AwUBOL6IezSYjBqwfc9jEQJZSgCgkeOipEFFjpk8FbbPzqC23PRUa5UAoOwH GWrrIy9SICIRvxWdFvqZIUQZ =6l49 -----END PGP SIGNATURE-----