Protect Your PC Against Viruses

Banish viruses before they can harm your system.


Viruses can easily spread to your system from the Internet, bulletin boards, and email attachments, and we're talking epidemic. Some are as benign as the common cold, and others can be as deadly to your hard drive as something from the movie "Outbreak." With thousands of known strains, there's a pretty good chance your computer will eventually encounter one. Today we're telling you how to protect your computer from viruses and to showing you how to cure it if it gets infected.


Inoculate

The best way to keep viruses off your PC is to install antivirus software. Here are a few options.


McAfee VirusScan
Norton Antivirus
AVG Anti-Virus (free)

These programs will check your system for known viruses, scan incoming files, and warn you before any infected files are let in. We strongly recommended that you set up your software to automatically scan for viruses 100 percent of the time. Your system take a little longer to boot up, but it's worth the extra wait.


Once you've determined that all the files in your system are virus-free, you should do a complete backup of your system. You'll really appreciate having clean copies of your files if you get infected thereafter.


Beware of attachments

Most viruses spread by email attachments and it's more than likely that an email attachment that contains a virus will come from a friend. Before you open attachments or downloaded files, scan them with your antivirus program. Also examine its file extension. Be very wary of any attachment with an extra extension, such as "happyfun.jpg.vbs."


Make sure your software keeps working

New viruses are released all the time and antivirus programs are only as good as their database of virus definitions. Set your program to automatically update so you never fall behind on your virus definitions. Also, regularly check for software updates at the vendor's website.


The Symantec Antivirus Research Center (SARC) maintains an up-to-date list of recently discovered viruses. This is a good site to check regularly, as the organization monitors the progress of computer viruses and offers a wealth of virus information and tools for removing them.


You know you have a virus when...


  • Unusual messages or displays on your monitor.
    Unusual sounds or music played at random times.
    Your system has less available memory than it should.
    A disk or volume name has been changed.
    Programs or files are suddenly missing.
    Unknown programs or files have been created.
    Some of your files become corrupted or suddenly don't work properly.
  • Another way you can detect viruses is by monitoring the byte size of programs installed on your hard drive, particularly of .exe and .com files. If you notice unexplained changes in file sizes, this is a good indication that your system has become infected.


My computer is has a virus. Help!

Here's what to do if you think your PC is infected.


1. Use your antivirus software
Scan your hard drive, disk drives, and all files downloaded to your system, including email attachments. In some cases infected files can be "cleaned" by your virus protection software. In others, the files will have to be discarded or quarantined.


2. Disconnect
Some viruses propagate across networks. It's a good idea to unplug your network connection if you find a virus during a virus scan.


3. Be happy you made a backup
In extreme cases, you may need to reformat your hard drive, destroying all the data on it. Then you'll have to reinstall your software and data, assuming you have the original software disks and clean backups of your files. In this case, you should install your virus protection software on the empty hard drive so you can verify that your backup files and original software are virus-free.


4. Warn your friends
Contact all the people you've recently exchanged information with via floppy disks, email attachments, Zip disks, or CD-R disks, and let them know that your system's been infected and theirs may be infected as well. Tell them what symptoms to look for or the name of the virus.

Types of Viruses

A computer virus is a piece of software designed to surreptitiously enter your computer system and infect your files. Typically, a virus will replicate itself and try to infect as many files and systems as possible.


Most viruses hide on removable media, such as Zip or floppy disks, in email attachments (not plain text messages alone), or on the Internet. If your system is infected and you save a file to a disk, you will probably infect the disk and any system that uses the disk.


Viruses can be written into almost any type of file, so you need to be careful when you add software to your system. Viruses have been accidentally included in licensed, shrink-wrapped software, but you are usually safe when installing legally purchased software obtained through normal channels.


A common myth is that viruses can be passed into your system only through executable program files or applications. You'd also think, then, that your computer couldn't get infected unless the program holding the virus is launched. Macro viruses, however, can exist inside any document whose application uses a macro language.


There are four types of computer viruses: boot sector viruses, file or program viruses, macro viruses, and multipartite viruses.


Boot sector viruses are usually transmitted when an infected floppy disk is left in the drive and the system is rebooted. The virus is read from the infected boot sector of the floppy disk and written to the master boot record of the system's hard drive. The master boot sector is the first place your system reads from when booting up from the hard drive. Whenever the computer is booted up thereafter, the virus will be loaded into the system's memory.


File or program viruses are pieces of viral code that attach themselves to executable programs. Once the infected program is run, the virus is transferred to your system's memory and may replicate itself further.


Macro viruses are the most commonly found viruses. They infect files run by applications that use macro languages, such as Microsoft Word or Excel. The virus looks like a macro in the file. When the file is opened, the virus can execute commands understood by the application's macro language.


Multipartite viruses have characteristics of both boot sector viruses and file viruses. They may start out in the boot sector and spread to applications, or vice versa.


Antivirus Resources Online

Antivirus software pages

Symantec Antivirus Research Center
Virus Bulletin
Virus Help and Information
Computer Virus Information

Antivirus software manufacturers

Symantec
McAfee
Trend Micro
Computer Associates

Free virus scanners

Trend Micro
PC PitstopPanda ActiveScan

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