Computer Viruses Essays (1326 words) - Computer Viruses,

Computer Viruses Almost every End-user in the world has heard of computer viruses and/or has had one at one point in time. Don't worry if you haven't heard about them, you won't find it in your bloodstream. Unfortunately you may find one in your computer memory or disk storage. ? Some may be as benign as the common cold and others as deadly to your hard drive as the Ebola virus ?. - 1 -What is a Computer Virus? ~ Usually defined as ? a malicious code of computer programming? it is actually just another software, only written with not so noble intentions. ~ A computer virus is designed to install, reproduce itself and cause damage to computer files and data without the users knowledge or permission. ~ A computer virus can only survive and attack in computer memory, which is usually RAM and disk storage. ~ You will not find a computer virus in your monitor or keyboard. How will the virus invade your computer? ~ All viruses enter the system through two main points. ~ Disk drive ~ Network adapter cards. ~ Disk drives may be any type (hard, floppy, CD and whatever you have). This makes anything you insert in your drive a possible source of infection. ~ The network adapter card is most likely your connection to the Internet. Viruses enter here most likely disguised as e-mail attachments. These attachments are often program files and office documents containing macros. Besides e-mail attachments, there are certain WebPages that contain harmful programming codes that may transfer into your computer as virus or virus-like codes. How do viruses spread? ~ After entering the computer memory, A virus often immediately sets out to multiply and spread duplicate copies of itself across the main data storage device. It does this by copying itself into as many files as it can on the disk drive. Later when users transfer or copy these files to their friends and colleagues, the virus can gain entry to all of their systems. If the virus has come this far on its path, the user may have permanent damage to data and hardware. Such a level of infection only happens to two types of users, those who do not install good anti-virus programs and those who do not update their programs on a monthly basis. As a result newer viruses can actually use the anti-virus programs to infect an even greater number of files. Four main types of viruses ~ 1) Boot sector viruses are usually transmitted when an infected floppy disk is left in the drive and the system is rebooted. The virus is read from the infected boot sector of the floppy disk and written to the master boot record of the system's hard drive. The master boot sector is the first place your system reads from when booting up from the hard drive. Then whenever the computer is booted up, the virus will be loaded into the system's memory. 2) Program or file viruses are pieces of viral code that attach themselves to executable programs. Once the infected program is run, the virus is transferred to your system's memory and may replicate itself further. 3) Macro viruses are currently the most commonly found viruses. They infect files run by applications that use macro languages, like Microsoft Word or excel. The virus looks like a macro in the file, and when the file is opened, the virus can execute commands understood by the application's macro language. 4) Multipartite viruses have characteristics of both boot sector viruses and file viruses. They may start out in the boot sector and spread to the applications, or vice versa. While not technically viruses, other malicious programs like worms and Trojan horses usually get stuck in there too. A worm is a program that replicates itself but does not necessarily infect other programs. Just like in the Greek myth, Trojan horses contain a concealed surprise. A Trojan horse program lies hidden in another seemingly harmless piece of software until some condition triggers its awakening. Why are they called viruses? The term virus is more recent, and was first used in 1984 by Professor Fred Cohen to describe self-replicating programs. The earliest PC viruses came a bit later in 1986. The name is appropriate because like a biological virus, a computer virus is