Safeguarding Your System from Computer Viruses

A computer virus is a malicious software program designed to do damage to your computer system by deleting files or even taking over your PC to launch attacks on other systems. A virus attacks your computer when you launch an infected software program, launching a "payload" that oftentimes is catastrophic.

Signs of Infection

How do you know whether your computer system has been infected with a virus?

In general, whenever your computer starts acting different from normal, it's possible that you have a virus. You might see strange messages or graphics displayed on your computer screen or find that normally well-behaved programs are acting erratically. You might discover that certain files have gone missing from your hard disk or that your system is acting sluggishor failing to start at all. You might even find that your friends are receiving emails from you (that you never sent) that have suspicious files attached.

If your computer exhibits one or more of these symptomsespecially if you've just downloaded a file from the Internet or received a suspicious email messagethe prognosis is not good. Your computer is probably infected.

How to Catch a Virus

Whenever you share data with another computer or computer user, you risk exposing your computer to potential viruses. There are many ways you can share data and many ways a virus can be transmitted:

• Opening an infected file attached to an email message

• Launching an infected program file downloaded from the Internet

• Sharing a floppy disk that contains an infected file

• Sharing a computer file over a network that contains an infected file

Of all these methods, the most common means of virus infection is via email. Whenever you open a file attached to an email message, you stand a good chance of infecting your computer system with a viruseven if the file was sent by someone you know and trust. That's because many viruses "spoof" the sender's name, thus making you think the file is from a friend or colleague. The bottom line is that no email attachment is safe unless you were expressly expecting it.

Practicing Safe Computing

caution

If you remember nothing else from this chapter, remember this: Never open an unexpected file attachment. Period!

Because you're not going to completely quit doing any of these activities, you'll never be 100% safe from the threat of computer viruses. There are, however, some steps you can take to reduce your risk:

• Don't open email attachments from people you don't knowor even from people you do know, if you aren't expecting them. (That's because some viruses can hijack the address book on an infected PC, thus sending out infected email that the owner isn't even aware of.)
  
  
• Download files only from reliable websites.
  
  
• Don't execute programs you find in Usenet newsgroups.
  
  
• Don't click links sent to you from strangers via instant messaging or in a chat room.
  
  
• Share disks and files only with users you know and trust.
  
  
• Use antivirus software.
  
  

These precautionsespecially the first one about not opening email attachmentsshould provide good insurance against the threat of computer viruses.

Disinfecting Your System with Antivirus Software

Antivirus software programs are capable of detecting known viruses and protecting your system against new, unknown viruses. These programs check your system for viruses each time your system is booted and can be configured to check any programs you download from the Internet. They're also used to disinfect your system if it becomes infected with a virus.

caution

Your antivirus software is next to useless if you don't update it at least weekly. An outdated antivirus program won't be capable of recognizingand protecting againstthe very latest computer viruses.

The most popular antivirus programs include

• AVG Anti-Virus (www.grisoft.com)
  
  
• Kaspersky Anti-Virus Personal (www.kaspersky.com)
  
  
• McAfee VirusScan (www.mcafee.com)
  
  
• Norton AntiVirus (www.symantec.com)
  
  
• PC-cillin (www.trendmicro.com)
  
  

Whichever antivirus program you choose (Norton AntiVirus is shown in Figure 29.1), you'll need to go online periodically to update the virus definition database the program uses to look for known virus files. As new viruses are created every week, this file of known viruses must be updated accordingly.

Figure 29.1. Use Norton AntiVirus to protect against computer viruses.