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Boot Sector Viruses


Boot sector viruses get into the master boot record. This is track one, sector one on your hard disk, and no applications are supposed to reside there. The computer at boot up checks this section to find a pointer for the operating system. If you have a multioperating system boot between Windows 95/98, Windows NT, and Unix, this is where the pointers are stored. A boot sector virus will overwrite the boot sector, thereby making it look as if there is no pointer to your operating system. When you power up the computer, you will see a Missing Operating System or Hard Disk Not Found error message. Monkey B, Stealth, and Stealth Boot are examples of boot sector viruses.


These are only a few of the types of viruses out there. For a more complete list, see your antivirus software manufacturer’s website, or go to Symantec’s website at
www.symantec.com/.

Updating Antivirus Components


A typical antivirus program consists of two components:


■    The definition files


■    The engine


The definition files list the various viruses, their type and footprints, and specify how to remove the specific virus. More than 100 new viruses are found in the wild each month. An antivirus program would be useless if it did not keep up with all the new viruses. The engine accesses the definition files, or database, runs the virus scans, cleans the files, and notifies the appropriate people and accounts. Eventually viruses become so sophisticated that a new engine and new technology are needed to combat them effectively.


Heuristic scanning is a technology that allows an antivirus program to search for a virus even if there is no definition for that specific virus. The engine looks for suspicious activity that might indicate a virus. Be careful if you have this feature turned on. A heuristic scan might detect more than viruses.

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