Protect Against Net Threats

They're out there, constantly morphing and multiplying: stealthy computer viruses, worms and spyware. Some are sent to annoy you or waste your time. The more sinister seek to vandalize your PC or steal your money.

To defend against these threats, most consumers bring in reinforcements -- four out of five computers have anti-virus protection, says the National Cyber Security Alliance, a coalition of government and private-industry groups. But three out of five computers that access the Web still harbor some type of troublemaker, reports a recent study by NCSA and America Online.

Antivirus software alone isn't enough, says Ron Teixeira, executive director of NCSA. Relying on only one barrier to keep out threats is like locking the front door but leaving the windows and garage wide open. It takes less than an hour to secure your PC against cyberspace invaders.

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Use security software. An antivirus program will detect and kill malicious code that's embedded in e-mail attachments and other downloads to your PC. You'll also want to wipe out spyware, which can hijack your computer or record your keystrokes to steal passwords and account numbers. A comprehensive program, such as Norton Internet Security ($70; www.symantec.com) or McAfee Internet Security Suite ($50 after a $20 rebate; www.mcafee.com), will do battle on both fronts. Or you can tackle each problem individually using free software, such as Grisoft AVG Anti-Virus (http://free.grisoft.com) plus either Spybot Search & Destroy (available at www.download.com) or Microsoft's AntiSpyware beta (www.microsoft.com).

Follow the program's prompts to enable its automatic-update feature to check for the latest versions at least once a week. And set up the software to provide real-time protection and to inspect every incoming file for signs of trouble. Schedule scans of your hard drive to run automatically -- once a day or once a week is best.

Patch your OS. Microsoft regularly issues patches to solve security problems in its Windows operating system. In Windows XP, go to "Security Center" in your control panel to ensure that the automatic-update feature is turned on. When your PC notifies you of an update, don't ignore it.

Secure your browser. Lower your risk by raising your Web browser's security settings to medium- or high-level protection. (On Internet Explorer, go to the "Tools" menu, select "Internet Options" and click the "Security" tab.) You can also green-light Web addresses you know and frequently visit (click on the "Trusted Sites" icon).

And be alert while you surf. Download only from reputable sources and be particularly careful with the Web freebies -- toolbars, screen savers, games and file-sharing programs are common sources of spyware. Before entering your credit-card number or other sensitive information on any Web site, check for a padlock icon in the lower right corner of your browser, and be sure that the Web address begins with "https" (s is for secure).

Handle e-mail with care. Viruses often piggyback on an e-mail message, so it's best not to open messages from unknown sources. Never open an attachment you weren't expecting, even from someone you know -- cyber thugs can make an e-mail's return address look familiar. One of the latest threats, the Sober.X worm, masquerades as an e-mail from federal investigators.

Read all messages in text-only format, not in HTML or rich-text format, and turn off the preview pane in your in-box. Viewing certain attachments in this window -- even without opening them -- may be enough to launch their attack. Scan all attachments for viruses before opening. Be wary of links embedded in e-mail messages. They could take you to a site infested with viruses or spyware. If the e-mail seems to be reputable, check out the link by manually typing the URL in your browser.

Raise a firewall. A firewall hides your PC from hackers and acts as a guard that inspects the files that enter and leave your computer. Windows XP comes with a one-way firewall already installed -- it inspects incoming communication to keep intruders out. But it doesn't examine outgoing data. For instance, a malicious program on your computer could attempt to send out your personal data. For greater protection, download a two-way firewall program, such as ZoneAlarm (free; www.zonelabs.com). Or use the firewall included in the comprehensive Norton or McAfee software.