Computer viruses are mysterious and grab our attention. They also show us how vulnerable we are. A properly engineered virus can affect a large percentage of computers on the worldwide Internet. Viruses in general are on the decrease, but occasionally one is created and that is when they make the news. In definition a virus is a self-replicating program that spreads by inserting copies of itself into other executable code or documents. So a computer virus behaves in a way similar to a biological virus, which spreads by inserting itself into living cells. In other words, the insertion of the virus into a program is termed infection, and the infected file or executable code that is not part of a file is called a host. Viruses are one of the several types of malware or malicious software. The term virus is often referred to computer worms and other sorts of malware. This can confuse computer users, since viruses are less common than they used to be, compared to other forms of malware such as worms. THis confusion can cause serious consequences, because it may lead to focus on preventing one type of malware over another, leaving computers open for more damage. Viruses can be intentionally destructive as destroying data; many other viruses are fairly benign or just annoying. Some viruses have a delayed effect, which is sometimes called a bomb. For example, a virus might display a message on a specific day or wait until it has infected a certain number of hosts. The main negative effect of viruses is their uncontrolled self-reproduction, which wastes or overwhelms computer resources.

            A short history of viruses starts with the program called"ElkCloner" which is credited with being the first computer virus to appear "in the wild", that is, outside the single computer or lab where it was created. Written in 1982 by Rich Skrenta, it attached itself to the Apple DOS 3.3 operating system and spread by floppy disk. Before computer networks became widespread, most viruses spread on removable media, particularly floppy disks. In the early days of personal computers, many users regularly exchanged information and programs on floppies. Some viruses spread by infecting programs stored on these disks, while others installed themselves into the disk boot sector, ensuring that they would be run when the user booted the computer from the disk. Since the mid-1990's, macro viruses have become common. Most of these viruses are written in the script language for Microsoft programs such as Word and Outlook. These viruses spread in the Windows environment by infecting documents and sending infected e-mail.

            Unlike biological viruses, computer viruses do not simply evolve by themselves. They cannot come into existence spontaneously, nor can they be created by bugs in regular programs. They are deliberately created b y programmers, or by people who use virus creator software. On the other hand, some virus writers consider their creations to be works of art, and see virus writing as a creative hobby. Moreover, they normally operate without asking for permission of the owner of the computer. Releasing computer viruses as well as worms is a crime in most jurisdictions. Non-resident viruses can be thought of as consisting of a finder module and a replication module. The finder module is responsible for finding new files to infect. For each new executable file the finder module encounters, it calls the replication module to infect that file. The replicators task is to open the new file, check if the file has already been infected, append the virus colde to the executable file, save the executables starting point, change the executables starting point so it points to the start location of the virus code, save the old start location to the virus in a way so that the virus branches to that location right after its execution, save the changes to the executable file, close the infected file, and return to the finder so that is can find new files for the replicator to infect.

            "The viruses are aimed at Microsoft and are rising sharply. The number of new viruses are worms aimed at Windows operating system rose 400 percent between January and June from the same-year-earlier period. Nearly 5,000 new Windows viruses and worms were documented in the first half of the year, up from about 1,000 in the year-earlier period. Symantec also said it expects more viruses and worms in the future to be written to attack systems that run on the Linux operating system and hand-held devices as they become more widely used" (Article A124007447"). There are numerous viruses that are continually showing up, so I will list just a few and give the links I found that show a list of the viruses. In November of 2004: X97M.Avone.A, Backdoor.Hacarmy.F, W32.Shodi.D, Trojan.Beagooz, Backdoor.Maxload, VBS.Yeno.C@mm. Links are as followed: , .

            Finally, there are two different approaches to security in computing. One focuses mainly on external threats, and generally treats the computer system itself as a twisted system. A computer system, itself is largely an untrusted system, and redesigns it to make it more secure in a number of ways. Chain of Trust is just one of the techniques that can be used to ensure privileged access is withdrawn when privileges are revoked. For example, deleting a user account should also stop any processes that are running with that user's privileges. A security system is no stronger than its weakest link. So in other words, computer viruses seem to be a problem that we will have to deal with as long as there are computers and people who think that creating a virus is a hobby and a form of creative art. So if you won a computer, PROTECT IT!