Checking Your Computer for Viruses

Just like you can get a virus, so can your computer. Computer viruses range from simple, mischievous programs that might display stupid messages to really dangerous ones that can wipe out all the data on a drive. How does your PC get infected? Well, you can get a virus from any number of sources, including the Internet, email attachments, and opening a file that happens to be infected from a floppy disk or other removable type of media (like a CD drive).

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Another nuisance that you need to protect your computer from is spyware. This is a program that installs itself, usually without your knowledge. It then tracks what sites you visit on the Internet and relays this information back to its owners. Checking for and removing spyware is covered in Chapter 8.

To protect yourself, you should get and use a virus scan program.

Checking System Security with Windows Security Center

New with Windows XP Service Pack 2 is the Windows Security Center. You can use this feature to get an overview of the security of your PC. You can also turn on any Windows features such as a firewall for Internet safety (covered in Chapter 8).

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You might think you are safe by scanning just program files. (Usually, these files have the extension .exe and are called .exe files.) It's a common myth that you can only get a virus from this type of file. Not true. You can get viruses from documents with macros, as in an outbreak of Word viruses that you could get simply from opening the infected document.

Don't just scan program files; be careful with other documents also, especially if they contain executable modules such as macros.

To view the status of security on your PC, follow these steps:

1.	Click Start, All Programs, Accessories, System Tools, Security Center. You'll see the Windows Security Center (see Figure 17.9). Figure 17.9. Use the Windows Security Center to review key security features on your system.
2.	Click the down arrow next to Virus Protection to view the status of this security item on your system.
3.	If Windows has recommendations, you see a button. Click Recommendations to review recommendations about better virus protection for your computer. Then click OK.
4.	Close the Security Center window by clicking its Close box.

Using a Virus Protection Program

With a virus protection program, you can periodically check your system for known viruses, scan incoming files, and be warned before any infected files are copied to your system.

Popular antivirus programs include Norton's AntiVirus (visit www.symantec.com for more information) and McAfee VirusScan (visit www.mcafee.com for product information).

Antivirus programs each work differently. Most are started automatically when you start Windows and then scan your computer at a set interval. You can also set them up to scan every file you open. Finally, you can start and run them at any time by double-clicking the program icon for the antivirus program or by selecting it from the Start menu. Figure 17.10 shows the disk and file virus-checking options for Norton's Anti-Virus program.

Figure 17.10. Use a virus program to periodically check your entire system for viruses.

For instance, you can set up the program to scan all floppy disks inserted into your system and all files that are downloaded to your system, including email attachments. Check your particular antivirus program's manual or online help for information on setting virus options.

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You need to update your antivirus program periodically. New viruses are created all the time, so if you don't have the latest upgrade, you can get a virus even if you are checking for viruses.

Handling an Infected File

When you scan for viruses, the program identifies any files that have been infected by any viruses it recognizes and usually offers you the option to repair the file if it can. In some cases, infected files can be "cleaned" by your virus protection software; in others, the files will have to be discarded. For really lethal viruses, you may have to reformat your hard disk and start over from scratch. In this case, you will be glad if you backed up your data (covered earlier in this chapter).

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Your antivirus program has a database of problems, viruses, and fixes. To make sure your program is working from the most recent list of viruses and fixes, you need to periodically update it. Many programs offer free updates for a period of time after their purchase. You can then subscribe for additional upgrades, and you should!