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This page is intended to assist faculty, students and staff in understanding some of the most important aspects of computer viruses and their prevention. As the way people exchange electronic information changes, so does the nature of viruses. Viruses are not to be ignored, but they can and should be dealt with in a calm and rational way.
What is a computer virus?
Viruses are computer programs that are designed to spread themselves from one file to another on a single computer. A virus might rapidly infect every application file on an individual computer, or slowly infect the documents on that computer, but it does not intentionally try to spread itself from that computer to other computers. In most cases, that's where humans come into the process. We send e-mail document attachments, trade programs on diskettes, or copy files to file servers. When the next unsuspecting user receives the infected file or disk, they spread the virus to their computer, and so on.
Where do viruses come from?
Since a virus is just a computer program, a virus can be produced by anyone that has some computer programming knowledge. Usually viruses are engineered by three distinct classes of people.
What can computer viruses do?
There are many things viruses can do. Usually a virus is assigned to do a single task, such as deleting non-system dependent files or programs (files used to run the programs you installed), deleting system files (files that your computer needs to function as a computer), renaming files, altering files, or displaying graphics. There are several different kinds of viruses.
A Trojan Horse program comes with a hidden surprise intended by the programmer but totally unexpected by the user. Trojan Horses are often designed to cause damage or do something malicious to a system, but are disguised as something useful. Unlike viruses, Trojan Horses don't make copies of themselves. Like viruses, they can cause significant damage to a computer.
Worms are like viruses in that they do replicate themselves. However, instead of spreading from file to file, they spread from computer to computer, infecting an entire network system.
Worms are insidious because they rely less (or not at all) upon human behavior in order to spread themselves from one computer to others. The computer worm is a program that is designed to copy itself from one computer to another, leveraging some network medium: e-mail, TCP/IP, etc. The worm is more interested in infecting as many machines as possible on the network, and less interested in spreading many copies of itself on a single computer (like a computer virus). The prototypical worm infects (or causes its code to run on) a target system only once; after the initial infection, the worm attempts to spread to other machines on the network.
Viruses are either benign or malignant. The majority of viruses are harmless and do no real damage to a computer or files. A benign virus might do nothing more than display a message at a predetermined time or slow down the performance of a computer. Malignant viruses cause damage to a computer system, such as corrupting files or destroying data. (These viruses don't corrupt the files they infect; that would prevent them from spreading. They infect, and then wait for a trigger date to do damage.) Just because a virus is classified as malignant does not mean that the damage it causes is intentional. Sometimes the damage is the result of poor programming or unintended bugs in the viral code.
A virus hoax is an e-mail that is intended to scare people about a nonexistent virus threat. Users often forward these alerts thinking they are doing a service to their fellow workers, but this causes lost productivity, panic and lost time. This increased traffic can soon become a massive problem in e-mail systems and cause unnecessary fear and panic.
What can I do to keep my system safe?
How do I obtain the latest upgrades and updates?
Contact the Help Desk for assistance.