October 22, 1999
Web posted at: 12:58 a.m. EDT (0458 GMT)
From CNN National Security Producer Chris Plante

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WASHINGTON (CNN) -- Marine Corps computer technicians were at work overnight Friday, improving security, after the Corps headquarters at the Pentagon was hit by a "worm virus," a Marine Corps source told CNN.

The Thursday afternoon attack infiltrated only "unclassified" computer systems, according to the source, and affected Microsoft programs only. Computer systems containing sensitive or "classified" information were not affected, he said.

The Marine Corps computer warriors were working with computer experts from Symantec Corp. to defeat the virus and retrieve lost files.

The attack left Marines around the Pentagon looking at blank pages where documents had once resided. Symantec installed Norton Anti-Virus software for the Marines.

While the military is a popular target for computer hackers, the Marine Corps official told CNN that Thursday's attack was from "a different strain or a virus we have not seen before."

"You went into your files and they were all empty," he said. Only computers at the Pentagon and the nearby Navy Annex to the Pentagon were infected by the virus, the official said.

The Pentagon has spent hundreds of millions of dollars in the last several years bolstering computer security, to combat attacks on computer systems from international foes, companies and domestic computer hackers.

The Marine Corps official said it was not clear how the virus entered its system.