The FUPA virus is a computer based virus that can corrupt several different programs on a network of computers. According to http://www.answers.com/topic/computer-virus?cat=biz-fin, a computer virus is a program that enters a computer (usually without the knowledge of the operator). Some viruses are mild, and only cause messages to appear on the screen, but others are destructive and can wipe out the computer's memory or even cause more severe damage.Computer viruses spread from machine to machine on disks and through telephone lines. Reports have come from engineers, architects, and also business firms. This virus has also been known to download random pictures off of the internet from any website a person has accessed, this can include any unwanted pictures from a webpage. This virus has the ability to spread through email and can crash an entire network of computers. It is advised that if you have the virus, don’t email different organizations because it can likely cause their systems to crash also. This virus is a resident virus. http://www.aarp.org/learntech/computers/howto/Articles/a2002-07-18-virus.html explains how a computer virus is spread: "Just as a human virus is passed from person to person, a computer virus is passed from computer to computer. A virus can be attached to any file that you copy to your computer. If you download files from the Internet or copy programs or files from friends on floppy disks, you are very susceptible to viruses. Actually, anytime that you download files or put a floppy disk into your computer, you are susceptible to viruses.
Many viruses are spread through e-mail. Generally, you cannot get a virus from simply reading e-mail. Certain types of today's viruses, like Klez, are different. They are very dangerous because you do not even have to open an e-mail attachment to release the virus. Just opening the e-mail itself can release the dangerous bug.
Under normal circumstances, a virus becomes active when you execute a program that contains the virus. For instance, if you download a program from the Internet and it is infected with a virus, the virus will attack your computer when you activate the program. Viruses are everywhere. Although it is rare, viruses have even been found in commercial shrink-wrapped software."Source: http://en.wikipedia.org/wiki/FUPA_virus