And while security experts are producing counterattack tools and bolstering preparedness for the high-tech logjam offensives, there is concern that defenders may not be able to keep up as they have less time to react.

Last week, the Internet service of The New York Times was paralyzed for more than two hours after company computers "started receiving a huge amount of electronic transmissions that flooded the machinery that protects the paper from hacker attacks," according to an e-mail from a Times systems administrator.

"A well-executed DoS attack just can't be defended against," SecurityFocus incident analyst Ryan Russell told NewsFactor Network.

More Machines

A recent report from the CERT Internet security center at Carnegie Mellon University indicated that denial of service attacks are getting easier to create and are having greater impact.

"The bar is being raised on what level of resources can be used for a DoS attack," CERT team leader for artifact analysis Kevin Houle told NewsFactor.

He said that while "garden variety" DoS attacks that use a single source to launch a flood of data packets continue to occur, a continuing trend is the use of several computers, known as "zombies," that are taken over by attackers.

"Essentially, with a single point of attack, there is a finite amount of traffic that can be produced, whereas a collection of several thousand attack points can generate much higher amounts of traffic," Houle said. "It is an escalation in terms of impact, and it has been a steady progression."

Perpetrator Protocol

Houle, who co-authored the CERT report on DoS trends, said attackers also are using new technologies and methods to stifle Web sites and Internet traffic.

"There is a move toward the use of legitimate protocols rather than the invention of new ones for attack modes," Houle said. "We've seen a trend toward the use of IRC-type (Internet Relay Chat) servers and networks as a central handler for DoS attacks."

Houle said the trend is troubling, as it makes DoS attacks easier to produce with a larger impact on legitimate, mainstream networks and protocols.

Common Victims

CERT reported that while more random, "blind targeting" attacks still occur, there is also a trend toward "selective targeting" of Windows-based systems, networks and users. However, Houle said, a total DoS meltdown on the Web is unlikely because of the different software and systems in use. (continued...)

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