A computer virus is a self-replicating code that does great harm to your computer, including the files in it. It has been around for the longest time but only became prevalent when the personal computer was introduced. The pc, together with the modem, the birth of the world wide web, and the rise of the computer hackers all gave the virus a so-called shot in the arm. Soon thereafter, millions of the world’s personal computers have fallen prey to these harmful viruses.
When a particular virus attacks your computer, it can either harmfully modify if not erase your important files or prevent your computer from functioning the way in its optimum level. Annually, it has been reported that computer virus infections have damaged some $8.5 billion worth of computer software and the industries that depended on their optimal functioning. These viruses are still around and remain prevalent, hence computer use should be very selective, if not strictly monitored by an Anti-virus software.
This list will give you information on the ten most harmful viruses ever created. You want to know just how harmful they are for your computer, then read on and be forewarned:
10. Melissa Virus
The Melissa virus was created by David L. Smith in 1999 and spread it through email. Posing as an important email attachment, once opened, the virus unleashes and sends itself to the recipient’s 50 email contacts. This virus wreaked so much havoc on private businesses and millions of personal computers all over the world.
9. ILoveYou Virus
The ILoveYou virus emanated from the Philippines and initally replicated through email. It posed as a love letter from a secret admirer. When opened, the virus replicates and hides itself in your personal computer’s registry and creates harmful files and destroys pertinent files. The damage it wrecked during its peak in 2000 surpassed that of the Melissa virus.
8. Klez Virus
The Klez virus, which was unleashed in 2001, was far smarter and more damaging that the Melissa and ILoveYou virus combined. While its mode of transmission is still via email, the virus has the ability to spoof itself and sends itself to all email addresses in the victim’s address book. Hackers only made the virus smarter, causing it to block the protection coming from Anti-virus softwares.
7. Code Red and Code Red II Virus
This virus exploited an operating system’s vulnerability of a personal computer. It has the ability to harmfully modify files and to delete them as well. One of the virus’ high-profile victims when it was unleashed in 2001 was no other than the White House.
6. Nimda Virus
The Nimda virus primary mode of transfer was not email but the world wide web – making it much more dangerous and harmful. A very fast and efficient virus, it spreads itself through the internet and makes access to the world wide web painfully slow – almost to a standstill.
5. SQL Slammer/Saphire Virus
This virus caused more than $1 billion damage when it unleashed itself in 2003. It mainly damages the web server system, making it very harmful to corporations and large businesses. This virus was responsible for Continental Airlines’ cancelling most of its domestic flights – when their eticketing system was downed by the Sapphire virus. The Bank of America’s atm service also crashed.
4. MyDoom Virus
The MyDoom virus spread itself through email. However, it had one more uncanny ability. It enabled to do a search in the internet’s major search engines using the email addresses that it had infected. This virus caused major search engines like Google to slow down and for some smaller search engines like the now-defunct Infoseek to completely crash.
3. Sasser and Netsky Virus
These viruses replicate itself once it has gained access on a computer. It then looks for other computers to infect and takes over the personal computer’s IP address. The infected computers now become very difficult to turn off without completely cutting the power source.
2. Leap A Virus
This is the first ever virus to infect a Mac computer. It transmits itself through Mac’s iChat system and sends the contacts of that particular iChat a corrupted attachment. This attachment further spreads the virus to other Mac users.
1. Storm Worm Virus
Unleashed sometime in 2006, this virus infects a computer and virtually makes that infected computer its remote control. It has the ability to send loads of spam mail and even block and replicate major anti-virus softwares.