Computer Viruses

A computer virus is hidden code within a program that may damage or destroy the infected files. Like living viruses, computer viruses require a host (such as a program file), and they’re designed to make copies of themselves. Typically, virus infections spread when somebody inserts a disk containing an infected program into a computer and then starts the infected program. You might also get a virus by downloading an infected program from the Internet. Most viruses are called file infectors because they attach themselves to a program file. When the program is executed, the virus spread to other programs on the user hard disk. Should you a copy a file on your computer to a disk and give it to someone, the infection spreads even further. Most computer viruses are spread by e-mail attachments. When you open an e-mail you may see a dialog box asking whether you want to open an attachment. Don’t open it unless you’re sure the attachment is safe. Consider the following scenario. A professor with large lecture section of 100 students receives an e-mail from a former student with an attachment named “Spring Break” that apparently contains a picture of the student’s spring break and so opens it. The attachment appears to do nothing, and the professor goes about his or her business. The attachment, however, is doing something. It is sending a copy of itself or everyone in the professor’s email address box-including each of the 100 students in the class. Now the attachment is propagating to the e-mail address lists of each of the students. The attachment is received by parents, friends, other professors, and fellow students. Many open the attachment, and the process accelerates very rapidly. Executable file attachments pose the most serious risk.