Tech_Tok(Introducing 5 Worst Computer Virus)

5 Worst Computer Viruses of All Time

Computer viruses can be a nightmare. Some can wipe out the information on a hard drive, tie up traffic on a computer network for hours, turn an innocent machine into a zombie and replicate and send themselves to other computers. If you've never had a machine fall victim to a computer virus, you may wonder what the fuss is about.

5: Melissa                                    

In the spring of 1999, a man named David L. Smith created a computer virus based on a Microsoft Word macro. He built the virus so that it could spread through E-mail messages. Smith named the virus "Melissa," saying that he named it after an exotic dancer from Florida [source: CNN].

4: ILOVEYOU       

A year after the Melissa Virus hit the Internet, a digital menace emerged from the Philippines. Unlike the Melissa virus, this threat came in the form of a worm -- it was a standalone program capable of replicating itself. It bore the name ILOVEYOU.

The ILOVEYOU virus initially traveled the Internet by e-mail, just like the Melissa virus. The subject of the e-mail said that the message was a love letter from a secret admirer. An attachment in the e-mail was what caused all the trouble. The original worm had the file name of LOVE-LETTER-FOR-YOU.TXT.vbs. The vbs extension pointed to the language the hacker used to create the worm: Visual Basic Scripting [source: mCafee].

3: The Klez Virus

The Klez virus marked a new direction for computer virus, setting the bar high for those that would follow. It debuted in late 2001, and variations of the virus plagued the Internet for several months. The basic Klez worm infected a victim's computer through an e-mail message, replicated itself and then sent itself to people in the victim's address book. Some variations of the Klez virus carried other harmful programs that could render a victim's computer inoperable. Depending on the version, the Klez virus could act like a normal computer virus, a worm or a Trojan horse. It could even disable virus-scanning software and pose as a virus-removal tool [source: Symantec].  

2: Code Red and Code Red Ii   

The Code Red and Code Red II worms popped up in the summer of 2001. Both worms exploited an OS vulnerability that was found in machines running Windows 2000 and Windows NT. The vulnerability was a buffer overflow problem, which means when a machine running on these operating systems receives more information than its buffers can handle, it starts to overwrite adjacent memory.

The original Code Red worm initiated a distributed denial of service (DDoS) attack on the White House. That means all the computers infected with Code Red tried to contact the webservrs at the White House at the same time, overloading the machines.

1: Storm Worm   

The latest virs on our list is the dreaded Storm Worm. It was late 2006 when computer security experts first identified the worm. The public began to call the virus the Storm Worm because one of the Emaikl messages carrying the virus had as its subject "230 dead as storm batters Europe." Antivirus companies call the worm other names. For example, Symantec calls it Peacomm while McAfee refers to it as Nuwar. This might sound confusing, but there's already a 2001 virus called the W32.Storm.Worm. The 2001 virus and the 2006 worm are completely different programs.

The Storm Worm is a Trojan horse program. Its payload is another program, though not always the same one. Some versions of the Storm Worm turn computers into zombies or bots. As computers become infected, they become vulnerable to remote control by the person behind the attack. Some hackers use the Storm Worm to create a botnet and use it to send spaammail across the Internet.