It would not take much for a malicious hacker to shut down the Internet, researchers at a meeting of the body that oversees Web address allocation warned on Tuesday. An attack designed to flood the Web's master directory servers with traffic "is capable of bringing down the Internet", Paul Vixie, a speaker at the Internet Corporation for Assigned Names and Numbers (ICANN) annual meeting, told Reuters. After the September 11 attacks on New York and Washington, non-profit corporation ICANN pushed other agenda items aside to concentrate the discussion on ways to keep the Internet safe. Adding to the impetus for the change in focus were the Code Red and Nimda Internet worms, which cast more attention on network security issues. Researchers said they were worried malicious hackers could attack the 13 "root" servers that direct computers to Web addresses, or domain names, or the 10 top-level domain servers, all of which serve as a kind of directory for the Internet To mount a so-called denial-of-service attack a malicious hacker would break into numerous PCs or Web servers and instruct them to send so much traffic to a target server that it would overload it, preventing people from accessing the Web. Such attacks are attempted all the time but usually to single Web sites and not on a scale that seriously interferes with overall Internet traffic, experts said. Another trouble spot is security at registrars, the companies which sell domain names, or Web addresses, experts said.
"Registrars are the weakest link," Steven Bellovin, an AT&T fellow, said during his presentation. "If the registrar is hacked and the database tampered with", it would be difficult for a domain name owner to prove ownership of a domain. Researchers would also like to prevent attacks that redirect Web traffic to a dummy site and e-mail to someone other than the intended recipient, said Paul Mockapetris, the inventor of the Domain Name System protocol and chairman of Nominum, which handles directory services for registrars.