07-09-2014, 10:30 PM
A computer virus is a coded program that is written in Assembly or a system programming language such as ‘C’ to deliberately gain entry into a host system and modify existing programs and/or perform a series of action, without user consent.[5] In the mid-eighties, so legend has it, the Amjad brothers of Pakistan ran a computer store. Frustrated by computer piracy, they wrote the first computer virus, a boot sector virus called Brain. From those simple beginnings, an entire counter-culture industry of virus creation and distribution emerged, leaving us today with several tens of thousands of viruses. Many people believe the worst a virus can do is format your hard disk. In fact, this type of payload is now harmless for those of us who back up our important data. Much more destructive viruses are those which subtly corrupt data. Consider, for example, the effects of a virus that randomly changes numbers in spreadsheet applications by plus or minus 10% at a stockbroker. Other nasty viruses post company confidential documents in your own name to some of the atlases Internet newsgroups, an act, which can both, ruin your reputation and the company’s confidentiality. Despite our awareness of computer viruses, how many of us can define what one is, or how it infects computers? This paper aims to demystify the basics of computer viruses, summarizing what they are, how they attack and what we can do to protect ourselves against them. A virus is nothing more than a program. A virus is a serious problem for everyone in the information technology industry. Viruses range from the harmless programs displaying a character on your screen to the malicious codes which go on to format your entire hard-disk. Just like a biological virus that takes over a living cell, a computer virus containing a set of coded instructions, also invades a host system and tries to replicate and infect new hosts. A sophisticated virus can spread undetected for a long time, waiting for a signal to begin destroying or altering data. A signal can be in the form of date, or a change in a system resource data, etc. The difference between a computer virus and other programs is that viruses are designed to self-replicate (that is to say, make copies of themselves). [8] They usually self-replicate without the knowledge of the user. Viruses often contain ‘payloads’, actions that the virus carries out separately from replication. Payloads can vary from the annoying (for example, the WM97/Class-D virus, which repeatedly displays messages such as “I think ‘username’ is a big stupid jerk”), to the disastrous (for example, the CIH virus, which attempts to overwrite the Flash BIOS, which can cause irreparable damage to certain machines). Many people believe the worst a virus can do is format your hard disk. In fact, this type of payload is now harmless for those of us who back up our important data. Much more destructive viruses are those which subtly corrupt data.