"Deadbolt" your computer and "don't talk to strangers," anti-virus expert advises.

Anson Lee, program manager at Symantec Corporation, parent company of the popular Norton Anti-Virus program, is fond of comparing one's computer security to home security. "The Windows anti-virus updates, which fix bugs and other known problems, are like fixing a broken window or a door lock in your home. The updates make it harder for hackers, giving them another obstacle to work their way through," Lee said.

Taking security one step further, Norton and other anti-virus programs, such as McAfee VirusScan Online, provide the equivalent of a "deadbolt" for your computer "door." Lee said he's amazed at how many otherwise reasonable people "open their doors to strangers" by opening e-mails and even attachments from senders they don't know.

"We're taught at an early age not to talk to strangers, but countless people do just that--unlock their deadbolts and open their computer doors to strangers by reading e-mail and opening attachments from unknown senders," Lee said.

SoBig.F virus

The August 22 invasion of a computer virus--or, more technically, a worm--named SoBig.F wrecked havoc on both personal computers and corporate computer systems worldwide. That was the term both the mainstream and the niche media invoked, "wrecked havoc."

SoBig carries an attachment that, if opened, instructs the infected computer to communicate with other host computers, further infecting them. If your computer becomes infected with the worm, an unauthorized person can remotely download and run programs on your computer, stealing confidential information from you, or use your computer to send spam. SoBig is expected to "reappear" in September.

We asked Lee what hackers' motives were--simple mischievousness, the challenge of breaking codes, vandalism, or the promise of monetary profit? "Mischievousness, yes, and vandalism," Lee said, "but there's a subset that also want to break into your computer to use it to access, for example, a profitable business database without leaving a trail. These hackers are more sophisticated, hiding their tracks."

Lee said that his company and others like it belong to a network called Internet Security Response, which they all connect to in the case of some virus like SoBig. "We are closing these doors," he said, "but even the most sophisticated anti-virus programs are not perfect. Everyone, every individual, has to be vigilant." That means you.

Firewalls

In addition to the simple steps mentioned above--installing anti-virus programs and keeping them up-to-date--Lee recommends that you install a firewall program (see accompanying Glossary), which is a guard that locks down a computer so someone else cannot access it. Lee said to "automate it to make it usable without a lot of detailed work."

Firewalls are especially recommended if you have a broadband connection.

What's the cost? Symantec, by way of example, sells its Norton Anti-Virus program for $49.95/year, the Norton Personal Firewall also for $49.95/year, and both programs for $69.95/year.

[e-mail]

Those using AOL are familiar with "mailer-daemon" messages, which indicate that your internet service provider did not accept your e-mail for some reason--usually because you've misspelled the recipient's e-mail address.

But AOL also advised its customers that they might receive messages from "mailer-daemon" these days because "someone you know is infected with the 'SoBig' worm."

But it's not necessarily true that if you are getting "mailer-daemon" messages, you are infected with the worm. "All it means is that your e-mail address was stored somewhere on an infected computer. You must update the virus definition file for your anti-virus software and then run an anti-virus scan of your computer to determine if you are infected with the worm," AOL advised its customers.

Symantec Corp., 20330 Stevens Creek Blvd., Cupertino, CA 95014, 408-517-8000, www.symantec.com