‘Worm’ Virus Poking Holes in Programming

The FBI on Friday tried to track the author of a computer virus that has hit some of the nation’s biggest corporations and wiped out files on tens of thousands of machines.

Software companies posted new virus-killing programs on their Web sites to attack the Worm.Explore.Zip virus, which enters machines in almost the same way as the recent Melissa virus--by disguising itself as a friendly piece of e-mail.

Melissa infected hundreds of thousands of computers, but there were signs Friday that the new virus may not be spreading as quickly. Still, it hit systems at leading technology companies such as Compaq Computer and Motorola and other major companies, including AT&T;, Boeing and General Electric.

The FBI would not reveal the methods of its investigation or how many computers were infected.

First detected in Israel early this week, Worm.Explore.Zip masquerades as a message from a friend or acquaintance: “Hi [Recipient Name]! I received your e-mail and I shall send you a reply ASAP. Till then, take a look at the attached zipped docs.”

The message is harmless unless the recipient opens an attached file. That unleashes a program that can wipe out the contents of documents, spreadsheets, graphic presentations and other important files created by Microsoft programs.

It also contaminates a computer’s e-mail program and sends a copy of itself as a reply to any incoming e-mail. That is particularly threatening for companies where workers regularly e-mail back and forth.

“Once the virus has started within an organization, it embeds itself into the system,” said Jan Kaminski, president of FastLane Technologies, a Canadian software company. “There’s nothing you can do until you actually remove some files from the machine.”

The virus is known to attack only those computers using Microsoft operating systems Windows 95, Windows 98 and Windows NT. Rival operating systems such as Macintosh and Unix apparently are not vulnerable.