What are computer viruses?
Microcomputer viruses are self-reproducing programs designed to move from computer to computer. Many are intended to be malicious but some cause no harm. Microcomputer viruses can be grouped into three categories according to their method of transmission and type:
* Boot-sector viruses are transmitted from machine to machine on infected floppies. Attempting to boot a machine from an infected diskette, even if the process is unsuccessful, can spread the virus.
* Executable-viruses are spread by running infected programs. The virus then infects subsequent programs as these programs are used.
* Macro-viruses are written inside certain applications like Microsoft Word. These viruses are spread by opening, saving, and printing affected document files. Typically, they corrupt documents (not limited to Microsoft Office documents).
* Worms are often put in the same category as viruses, but are distinctly different. A virus file is usually a self-contained program that a person executes. A worm is an automated way of hacking into computers. The worm finds computers missing security patches and without a firewall, hacks those computers, then uses those computers to hack new computers.
What can be done to avoid infection?
Most common viruses are spread by email, sharing files over the Internet or by moving floppy disks from one computer to another. Worms are spread by not following secure computing practices ( see The ITS Security Page). To detect, remove, and prevent the spread of computer viruses and worms, ITS currently distributes Symantec Antivirus Corporate Edition 9.0 for Microsoft Windows and Norton Antivirus 9 for Mac. They are available for download at software.usc.edu.
There are other commercial virus protection packages available, however ITS does not support their use.