The "Nachi" worm propagates via MSRPC DCOM and the IIS WebDAV bug. It may be causing this storm because it runs 300 scanning threads, and it pings each IP first. http://xforce.iss.net/xforce/alerts/id/150 MS Blast wasn't multithreaded. Regards, =============================== Daniel Ingevaldson Engineering Manager, X-Force R&D dsi@iss.net 404-236-3160 Internet Security Systems, Inc. The Power to Protect http://www.iss.net =============================== -----Original Message----- From: Paul Jasa [mailto:pjasa@univision.net] Sent: Tuesday, August 19, 2003 12:19 PM To: nanog@merit.edu Subject: AT&T Blocking ICMP (was RE: AT&T US Network Slowdown?) A call to AT&T Worldnet confirms that AT&T Worldnet service is blocking ICMP in order to deal with an undefined emergency. Nothing posted on their site, nor any other info is available. If anyone has info related to this "icmp outage", please advise. Thanks! pj ====================================== Paul Jasa Network Engineer ====================================== -----Original Message----- From: Sean Crandall [mailto:sean@megapath.net] Sent: Tuesday, August 19, 2003 02:12 AM To: Paul Jasa; nanog@merit.edu Subject: RE: AT&T US Network Slowdown? Importance: High

Dear Nanogers, Is anyone aware of a "slowdown" issue throughout the US AT&T network since 8/18 at around 4pm which is causing a lot of internet circuits (including DSL) to be inaccessible and/or appear down from the outside world? AT&T says this has been escalated to "Level 4" with no ETA and affecting the whole country. I am seeing this problem in the San Francisco area. Just wondering if anyone else is experiencing anything that would confirm AT&T's claim, and fishing for more info about the possible cause and ETA. Thanks!

We are currently seeing the slowdown on our network in San Jose. Started about exactly the time frame that you mentioned. The rest of the country (oddly) seems unaffected by this at the moment, but San Jose is getting hammered by something. Still trying to sort out exactly where it is coming from. -Sean Sean P. Crandall VP Engineering Operations MegaPath Networks Inc. Pleasanton, CA 94588 (925) 201-2530