A worm hit the UCSB computer network late Wednesday night, causing some departments, organizations and residence halls to lose their Internet connections.

Todd Atkins, network security coordinator for the Office of Information Technology, said a variant of the PhatBot worm made its way into the network around 10 p.m. Wednesday. About 500 machines on campus were infected with the worm, Atkins said, but systems administrators did not report any damages caused by it and the majority of the network was operational again around 12:30 a.m. Thursday. PhatBot did not pose a large threat to the university’s computer network, Atkins said.

“I would say we’ve seen worse worms on this campus,” he said. “It’s not as bad as CodeRed or anything like that.”

A worm is a virus that has the ability to propagate, or multiply by using the resources of one machine to infect other machines. Which variant of the Phatbot worm attacked the campus network or where it originated from is unknown, but Atkins is investigating the incident.

When Phatbot started to propagate, the staff on duty at the campus networks operations center noticed spikes in network traffic and contacted Atkins. The team then blocked network traffic from infected machines and notified local systems administrators of the problem.

New networking equipment installed this year is part of the reason Phatbot did not cause widespread damage, Atkins said.

“If we were to see something like Slammer in December, we had to cut off traffic to that machine in five minutes,” he said. “With the new equipment we have today, we could have a few machines infected, but our network equipment would be able to handle it.”

Not all computers and networks on campus were infected, Atkins said, because he could connect to on-campus machines from home.

“I was looking at this problem at home, so I wasn’t having any connectivity problems,” he said.

But Atkins said universities in Chicago and Virginia may have also been infected with the worm, but he will not know for certain until he investigates further.