Top 10 Worst Viruses

You must have remembered the messages like Trojan, worm and shortcuts.exe when you are debugging your Personal Computer using an antivirus well for many of us these are simple viruses which tends to corrupt windows or any operating system. Infact it isn’t so every virus has its own unique characteristic and tends to replicate itself once activated. Have a look to the following list;

10: Melissa

During the year 1999, a software genius named David L. Smith created a computer virus which was based on the Microsoft Word macro. The virus has its characteristics of spreading messages through electronic mail. The name proposed for the virus by Smith was Melissa; accounts suggest that it was the name of an foreign dancer from Florida.  The Melissa computer virus persuades recipients into opening a document with an e-mail message like “Here is that document you asked for, don’t show it to anybody else.” Once triggered, the virus duplicates itself and propels itself out to the top 50 people in the recipient’s e-mail address book.

9: ILOVEYOU

Only after a year of the creation of Melissa virus another digital hazard came into existence from the area of Philippines. The Threat or Virus was in the form of Worm and it was a standalone program having the capability to duplicate itself. The name given to this worm was ILOVEYOU. During the initial stages the virus travelled through email messages similar to the way Melissa travelled. The message says that the email is from a secret admirer and wants to convey you his/ her feelings. 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.

According to anti-virus software producer McAfee, the ILOVEYOU virus had a wide range of attacks:

• It copied itself several times and hid the copies in several folders on the victim’s hard drive.
• It added new files to the victim’s registry keys.
• It replaced several different kinds of files with copies of itself.
• It sent itself through Internet Relay Chat clients as well as e-mail.

8: The Klez Virus

The Klez virus manifested a new way for computer viruses, raising the bar high for those that would go after. It debuted in the year 2001, and deviations of the virus overwhelmed the Internet for numerous months. The basic Klez worm infected a victim’s computer through an e-mail message, duplicated 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 untreatable. 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: Symentec

7: 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 operating system 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 Web servers at the White House at the same time, overloading the machines. Source: How stuff works

6: Nimda

In the year 2001 another kind of virus spread throughout the internet which was named Nimda. The virus type was worm; it became the fastest propagating computer virus at the time.  In fact, according to TruSecure CTO Peter Tippett, it only took 22 minutes from the moment Nimda hit the Internet to reach the top of the list of reported attacks. The prime targets of Nimda were Internet servers side by side affecting the home PCs. The main purpose was to bring Internet Traffic to a crawl. The Nimda used multiple ways for spreading including e-mail, its multiple travel characteristic made it, spread the virus across multiple servers in record time.

5: SQL Slammer/Sapphire

In the year January 2003, a new Web server virus extends across the Internet. Many computer networks were unsuspecting for the assault, and as a result the virus brought down numerous significant systems. The Bank of America’s ATM service stopped, the city of Seattle suffered outages in 911 services and Continental Airlines had to cancel several flights due to electronic ticketing and check-in errors.

4: MyDoom

The MyDoom virus is an additional worm that can generate a backdoor in the prey computer’s operating system. The original MyDoom virus there have been numerous alternatives had two elicits. One elicit caused the virus to start a refutation of service (DoS) attack starting Feb. 1, 2004. The second elicit controlled the virus to stop issuing itself on Feb. 12, 2004. Even after the virus stopped spreading, the backdoors generated during the first infections remained live.

3: Sasser and Netsky

A 17 year old German named Sven Jaschan produced the two programs and freed them onto the Internet. While the two worms worked in dissimilar ways, similarities in the code led safety experts to consider they both were the work of the same person. The Sasser worm attacked the computers through Microsoft Windows vulnerability. Disregarding to other similar worms it didn’t spread through email rather it travelled through open internet source. Once it demolished a computer system it looked for other potentially vulnerable computer systems. It searches for random IP addresses to find vulnerable computer systems, contacts them and then instructs them to download it.  The virus also tainted the victim’s operating system in a way that made it tricky to shut down the computer without cutting off power to the system.

2: Leap-A/Oompa-A

You must have heard that Mac computers are invulnerable towards viruses, is that actually true? Is it? So the answer lies here, for the most part, that’s true. Mac computers are partly protected from virus attacks because of a concept called security through obscurity. But the world is not enough; a Mac hacker has breached the Mac security recently. In the year 2006 the Leap-A virus, also known as Oompa-A, debuted. It uses the iChat instant messaging curriculum to propagate across vulnerable Mac computers. After the virus infects a Mac, it searches through the iChat contacts and sends a message to each person on the list. The message contains a corrupted file that appears to be an innocent JPEG image.

1: Storm Worm

The most deadly virus in our dreadful list of viruses is known as the Storm Worm. It was the year 2006 when or the first time security experts first identified the above said worm. The community began to name the virus the Storm Worm because one of the e-mail messages carrying the virus had as its subject “230 dead as storm batters Europe.” Different antivirus producing companies call the worm with different names; For example, Symantec calls it Peacomm while McAfee refers to it as Nuwar. The type of 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. This makes the computer easily approachable to the person who is behind the following attack plan.