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Introduction to Viruses

A computer virus is software used to infect a computer. After the virus code is written, it is buried within an existing program. Once that program is executed, the virus code is activated and attaches copies of itself to other programs in the system. Infected programs copy the virus to other programs. The effect of the virus may be a simple prank that pops up a message on screen out of the blue, or it may destroy programs and data right away or on a certain date. It can lay dormant and do its damage once a year. A distinction should be made between a virus and a worm.  These infections are often created by social engineers, who illegally enter computer systems by having persuaded an authorized person to reveal IDs, passwords and other confidential information.

Another way of receiving viruses is through attachments in e-mails. Junk e-mail often includes attached files which have viruses or worms encoded in them. People often install Anti-Virus software in an attempt to scan their computer for malicious software and other hoaxes. They scan computers searching for viruses matching definitions in a virus dictionary, or they identify suspicious behavior from a computer virus which might indicate infection.