Net's Vulnerability Exposed

Attack on root servers resulted in moderate damage - this time

Last week's assault on the Internet's core addressing system may not have caused much real damage, but it highlights the Internet's vulnerability to more sophisticated cyberattacks in the future, security analysts warned.

All 13 of the Internet's root Domain Name System servers—three of which are located outside the U.S.—were victims of a massive distributed denial-of-service attack on Oct. 21.

"It was the single most elaborate and focused attack on the DNS network that we have ever seen," said Tom Ohlsson, vice president of Matrix NetSystems Inc., an Austin, Texas-based Internet performance monitoring company.

The attack appears to have been an attempt to disrupt the Internet by clogging root DNS servers with useless traffic. The root DNS servers provide the vital translation services needed for converting a Web name such as into a corresponding numerical IP address.

But overall Internet service appears to have been largely unscathed, with few major disruptions reported, Ohlsson noted.

That's because most of the information contained in the 13 root DNS servers is cached in redundant and hierarchical fashion across multiple secondary DNS servers.

"On the plus side, this shows that despite all those apocalyptic projections, the Internet is more resilient than people think," said John Pescatore, an analyst at Gartner Inc. in Stamford, Conn. "But it also shows that the basic plumbing of the Internet still has vulnerabilities that need to be addressed or brought up to business-quality levels."

Simple Solution

The relatively simply nature of last week's DDOS attack is what made it easy for administrators to detect and choke off the offending traffic in a few hours, analysts said.

But service would have started degrading if the attack had been sustained long enough for the information contained in the secondary DNS caches to start expiring—a process that usually takes from a few hours to about two days, analysts added.

"This wasn't exactly the most sophisticated attack in the world," said Jerry Brady, chief technology officer at Guardent Inc., a security consultancy in Waltham, Mass. "But I've got to believe that this is going to inspire a lot more attacks like this in future."

In a DDOS attack, hackers typically break into and take over thousands of poorly protected networked computers—including those in homes—and use such "zombies" to send torrents of useless data at target servers or networks.

"It is the electronic equivalent of somehow getting 50,000 phones to dial 911 at the same time," said Mark D. Rasch, former head of the U.S. Department of Justice's computer crimes unit and currently senior vice president and chief security counsel at Solutionary Inc.

The Internet Corporation for Assigned Names and Numbers (ICANN), the private group that's charged with ensuring the stability and security of the DNS, will discuss methods for improving DNS security at its annual meeting next week in Shanghai.

Among the fixes ICANN will be looking at is deploying the DNS Security protocol to improve data origin authentication, said Stephen Crocker, an Internet pioneer and computer scientist who heads the ICANN security committee.

The more daunting problem is improving the security of PCs sold without any security protections. "It's a public nuisance issue," Crocker said.

And DNS servers aren't the only component of core Internet infrastructure that can be taken down by such attacks, analysts say. For instance, an attack directed against a few well-selected Border Gateway Protocol routers—which are used to exchange routing information for the Internet—could cause large portions of traffic to be misdirected at will, said Ted Julian, president of Arbor Networks Inc., a Lexington, Mass.-based vendor of DDOS prevention tools.

Last week's attacks "represent an important escalation of these kinds of threats," Julian said. "DDOS is no longer being targeted at single Web sites, but at the entire Internet infrastructure."

DNS Servers

Thirteen geographically distributed root name, or DNS, servers operated are by nine independent organizations.

Ten of the servers are located in the U.S.; the others are in Japan, Sweden and England.

The root name servers are operated by the U.S. military, commercial organizations, nonprofit organizations, Internet service providers, universities and research institutes.

Source: ICANN, Marina Del Rey, Calif.

Copyright © 2002 IDG Communications, Inc.

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