-----BEGIN PGP SIGNED MESSAGE----- =============================================================================== Security Advisory CERT-NL =============================================================================== Author/Source : Niels den Otter Index : S-98-01 Distribution : World Page : 1 Classification: External Version: 1 Subject : "smurf" IP Denial-of-Service Attacks Date : 9-Jan-98 =============================================================================== By courtesy of CERT Coordination Center we received information on denial-of-service attacks involving forged ICMP echo request packets (commonly known as "ping" packets) sent to IP broadcast addresses. These attacks can result in large amounts of ICMP echo reply packets being sent from an intermediary site to a victim, which can cause network congestion or outages. CERT-NL urges you to disable IP-directed broadcasts at your routers that are connected to large LANs and to configure your operating systems to prevent the machine from responding to ICMP packets sent to IP broadcast addresses. All CERT Coordination Center advisories are mirrored by CERT-NL. The specific URL for this case is: ADVISORIES ARE REGULARLY UPDATED BY CERT COORDINATION CENTER. Therefore we advise you to check on our mirror regularly - you can automate this process using the CERT-NL notifier service. More information about the CERT-NL mirror and notifier services is contained in News items N-95-01 (notifier) and N-95-02 (CERT mirror), both present on ============================================================================== 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://www.surfnet.nl/surfnet/security/cert-nl.html ftp://ftp.surfnet.nl/surfnet/net-security 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 52 87 92 82 ALTIJD BEREIKBAAR EMERGENCIES : +31 6 52 87 92 82 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: 2.6.2i iQCVAwUBNLYThVpSTqmIRWKVAQGv2gQArpNircZyfLA81bSd13d0qMKjas/ZVY8b bhUJVHOMMzgBu+0EUmUr7dODxOQOZ7ClQAaWmycXIZpIAQaK6O39aQBfKaVZNM4i 9faWyiW3drJwj0rCgK6cqp5Pez1eK3HnkCFS6h3cdMMcTP+IHCI/5smTplHFgAgc MZmqqqjHnnc= =HaeF -----END PGP SIGNATURE-----