Computer virus
computer virus is a harmful software program written intentionally to enter a computer without the user's permission or knowledge. It has the ability to replicate itself, thus continuing to spread. Some viruses do little but replicate, while others can cause severe harm or adversely affect the program
and performance of the system. A virus should never be assumed harmless and left
on a system.
There are different types of viruses which can be classified according to their origin, techniques, types of files they infect, where they
hide, the kind of damage they cause, the type of operating system, or platform they attack. Let us have a look at few of them.
Most viruses are pretty harmless. The user might not even notice the virus for years. Sometimes viruses might cause random damage to data files and over a long period they might destroy files and disks. Even benign viruses cause damage by occupying disk space and main memory, by using up CPU processing time. There is also the time and expense wasted in detecting and removing
viruses.
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VIRUS
A virus is a small snippet of code that has no ability to function on its own and needs a
host executable or document in order to function, thrive, propagate, and
ultimately deliver its payload.
Why do people write and spread viruses?
It is difficult to know why people write them. Everyone has their own reasons. Some general reasons are to experiment how to write viruses or to test their programming talent. Some people just like to see how the virus spreads and gets famous around the World. The following is a list from news group postings alt.comp.virus and tries to explain why people write and spread viruses.
1- They don't understand or prefer not to think about the consequences for other people.
2- They simply don't care.
3- They don't consider it to be their problem if someone else is inconvenienced.
4- They draw a false distinction between creating/publishing viruses and distributing them.
5- They consider it to be the responsibility of someone else to protect systems from their creations.
6- They get a buzz, acknowledged or otherwise, from vandalism.
7- They consider they're fighting authority.
8- They like 'matching wits' with anti virus vendors.
9- It`s a way of getting attention, getting recognition from their peers and their names (or at least that of their virus) in the papers and the Wild List.
10- they`re keeping the anti virus vendors in a job.
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Famous Computer Viruses
By famous we mean those viruses and worms that have affected millions of machines leading to huge social and economical damages. Throughout history you will come across a huge list of computer viruses and
worms created by man, but the names mentioned here are the most dangerous ones.
I LOVE YOU
I think everyone who has owned a computer has heard about this dreaded virus. I LOVE YOU is believed to be one of the most
dangerous computer invention among viruses, worms and Trojans. It was developed by VBScript and was discovered on 4th May 2000 in Philippines. In just 24 hours it had affected PCs in every country of this world leading to a loss of USD $5.5 billion. Everything started from an email message which arrives in the user's inbox with I LOVE YOU as the subject. After entering the system, the virus used to attach a copy of itself on each file of the computer. In addition to this it used to send a copy of itself to all the users who would be on the victim's
contact list. All the affected users had a Windows Operating System.
Conficker
Ranking at #5 in the list of most dangerous computer viruses, Conficker was born in November 2009 and it affected more than 5 million PCs in a short span of time. It is credited for creating a secure worldwide infrastructure for cyber crime. This worm duplicates itself and spreads via a buffer overflow weakness in the server of machines using Windows Operating Systems. Once in the machine it affects services like Windows Update, Windows Defender, Windows Security Center and Windows Error Report. Today having the best antivirus you can is a good option as it is able to destroy this worm which had created hell in countries like India, China and Brazil.
Sasser
This nasty worm ruined everything and was the talk of the Internet for manymonths. This computer virus spread by penetrating into a vulnerable network. It create havoc wherever it went, from the British Coast Guard to Delta Airlineswhich had to cancel some of its flights after its systems were infected by Sasser.
Asprox Botnet
A very new virus, the Asporex Botnet is the reason for many phishing scams. Discovered in 2008, the Asporex Botnet has been used to launch many high profile attacks on different websites to spread malware. The Botnet makes itself ready in a very unusual way and infects mostly those websites which are running Active Server Pages. The Botnet always attacks in waves and each wave is designed to infect as many websites as
possible.