We all know that viruses caninfect and damage your computer or laptop. Viruses are around everywhere and are affecting computer on daily basis at very high speed. Over the decades there have been some very dangerous computer viruses, and here are the top 5.

The Slammer

The Slammer virus was released in January 2003 and South Korea was the most affected nation. It is basically a web server virus that aimed to spread throughout the Internet. As no one was prepared for it, therefore it affected many home users and business related systems. It caused huge threat in everyday life by affecting ATMs, airline systems and Internet cafes. Eventually antivirus software was created to deal with the Slammer, but by then it had already caused damage that is more than one billion dollars. .


MyDoom affected computers in 2004 and various types of the same virus was released. It is a worm that operatsby creating backdoor access in the PCs operating system. It spread via e-mails and between user networks. The first event saw the virus being activated and replicating itself to cause denial of service. Just less than two weeks later, another event occurred that stopped the virus from replicating. The problem was that the backdoor created were still present, and this caused huge issues for household desktops and search engines.

Sasser and Netsky

The Sasser and Netsky viruses were two different viruses created by the same person. They operated in different ways but they had similar codes. The Sasser virus spreads via vulnerable systems and looks for non protective programs. These programs would then download the virus, leading to serious disturbances within the operating system. Netsky on the other hand spread through e-mails causing a denial of server service. These viruses were so potent that specialists suspected it constituted one quarter of all viruses online, at that particular time.


It is widely believed that viruses only attack PCs and not Macs, because Apple has created its hardware and software in such a way that its products are protected. Unfortunately Leap-A was the virus that brought the exception to the rule. It was released in 2006 and used the instant messaging program called iChat in order to propagate itself. It would send seemingly innocent messages to all contacts in the list, which actually contained a corrupt file.

Storm Worm

The Storm Worm takes the top spot. It is a Trojan horse that was first identified in 2006.It spread via e-mail using the subject title of “230 dead as storm batters Europe.” As the months went by the title was changed to reflect current happenings. Whenever users clicked on links to pages and videos they would end up downloading the virus. It is considered the worst of all time so far, is that it affected the most amount of systems, to the tune of 200 million e-mails in several days.

More viruses will no doubt be released in the future, and there is no telling what they will do to our systems.