Worms trapped in the tarpit are unable to move along to infect other computers. Stuck hackers first waste their time flailing away at a non-existent machine; they are then forced to shut down their hacking program or computer to escape.

Viruses are growing in sophistication and are thus able to propagate themselves faster and more effectively, the company said in a statement regarding the Nimda virus.

Nimda is a hybrid virus that contains a mass-mailing component, enabling it to spread very quickly. As it spreads, it attempts to infect Web servers with a version of the Code Red program which caused serious disruption last month. Current outbreak tracking statistics show this to be one of the fastest-spreading viruses to date, MessageLabs said.

A recent public opinion poll surveying reactions to the terrorist attacks reported that 72 percent of respondents believed that reducing encryption to aid the CIA or FBI would be "somewhat" or "very" helpful in preventing similar incidents. The study, conducted by Princeton Survey Research Associates for Washington's Hotline newsletter, found that 54 percent of those surveyed felt encryption laws should be reduced to assist investigators.

Grifter: Well, that proves it, at least 72% are complete and total idiots. "This country could be really safe, if we just give up all of our rights, let's do that!!!"

The changes, which have since been removed, were made to an Aug. 23 Reuters story about the Russian software programmer Dmitry Sklyarov, who stands accused of violating U.S. copyright law.

According to Yahoo, news of the hack was first reported and brought to the company's attention by SecurityFocus.com this week. A Yahoo representative said the Web portal had taken "appropriate steps to block unauthorized access" to its production tools.