A virus that has crippled campus computer networks across the country has forced University officials to begin filtering e-mails in an unprecedented attempt to keep Harvard’s servers running.

Harvard Arts and Sciences Computer Services is universally deleting incoming e-mails infected with the Sobig.f virus.

The software currently in use to identify and delete e-mails specifically carrying the computer virus netted 36,000 messages in its first nine hours online, according to Coordinator of Residential Computing Kevin S. Davis ’98. All mail sent out by the Sobig virus has a unique, characteristic signature of digits which is easily identifiable by the filtering software.

The solution, which is unusual in that it does not allow users to opt-out of the filtering, is an “emergency” measure, according to Davis.

“This really was the only thing we could do to keep the systems up,” he said.

To provide longer-term protection against the Sobig virus and other e-mail based bugs, HASCS is also testing a new central server-based virus scanning program for e-mail.

Application of this system will only be voluntary. Network users will not be required to utilize it, Davis said.

“The challenge in a university is that it must be an open environment. There are people doing research who need unfettered access,” Davis said. “So this broader scanning will be strictly on opt-in basis.”

Sobig sends e-mails 10 to 20 times the size of a normal message out from infected computers.

Another recent threat to computer networks, the Blaster worm, exploits a hole in Windows 2000 and XP to infect a computer.

Though neither virus deletes material from infected computers, both both multiply and overload networks, causing significant slowdowns.

“The good thing is that they’re both fairly easy to deal with,” Davis said. “The danger is in the derivative versions that are being made.”

While Blaster has been present since the summer school term, Sobig is a relatively new threat, Davis said.

“It’s [Sobig that has] been affecting students already—our mail volume has been significantly higher,” Davis said. “It’s quite good at spreading quickly and leaving behind undesirable software on people’s computers.”

To attack the Blaster worm, HASCS has provided a patch on their website that will fix infected machines by closing the vulnerability that the worm and its variants exploit to attack computers. But Blaster hits systems so quickly that students must install the patch immediately upon connecting to the network, Davis said.