Top Ten Worst Computer VirusesWorms. Trojans. Viruses. If your life hasn't been disrupted by a malicious piece of software, consider yourself lucky. The number of unique computer viruses in circulation topped one million in April 2009. These viruses can be programmed to email your friends and steal your credit card information. One even attempted to alter the spin of Iran's centrifuges.
So which of these viruses have the dubious honor of being the worst?
- 10. Code Red. Discovered in July 2001, this worm was named partially because the programmers who discovered it were drinking Code Red Mountain Dew and partially because the virus made itself known by defacing websites with the message "HELLO! Welcome to http://www.worm.com! Hacked By Chinese!" Besides coining a new phrase that would become popular with hackers everywhere, Code Red was time released. After installing itself, it waited quietly for about a month. Then it launched denial of service attacks against a preprogrammed list of sites that included the White House. By the end of August, Code Red had infected 150,000 computers and was estimated to have caused $2.6 billion worth of damage.
- 9. Sasser. One month after Sasser began worming its way through network ports, mi2g, a digital risk-management firm named it the 5th worst malware of all time. Sasser caused infected computers to continually reboot. This worm shut down satellite communications for news agencies in France and caused flight cancelations. A German named Sven Jaschan was arrested for writing and distributing the virus. Sasser's release date, not uncoincidentally, was Jaschan's 18th birthday. Because he was a minor when the virus was written, Jaschan received a 21-month suspended sentence.
- 8. Stuxnet. The Stuxnet worm had been around for almost a year before it was officially discovered in March 2010. Stuxnet only activated if it found Siemens' software on a computer. This worm was designed to control machinery--and its goal was to force Iran's nuclear centrifuges to spin out of control while making it looking like nothing unusual was happening. The full plan failed, but Stuxnet did affect Iran's operations. Did the government of Israel unleash Stuxnet? What about the United States? No one knows. What we do know is that Stuxnet demonstrated that a file hiding on a USB drive could be used to target industrial-control systems and breach international security.
- 7. Melissa. Melissa was the first mass mail virus. Originally posted to a pornography newsgroup on March 26, 1999, Melissa spread like wildfire. This macro virus infected Microsoft Word documents and then mailed itself to 50 addresses in the victim's Outlook address book. Ultimately, Melissa infected 20% of North American computer systems, shut down servers across the country and caused $80 million in damages. It didn't take long to find the virus writer. Less than a week after he planted it, David Smith was arrested. He was eventually sentenced to 20 months in prison.
- 6. Nimda. Nimda was a proof-of-concept virus, written to show just what a virus could do. When doors were locked, this worm came through the window, spreading infection through email, open network shares, html files, Microsoft directory vulnerabilities and back doors left open by previous virus infestations. Nimda attacked servers and slowed Internet traffic. According to Computer Economics, a popular website for IT metrics, Nimda caused over $635 million in damage.
- 5. Klez. Klez first appeared in October of 2001. By the time its "H" variant appeared, Klez had been named the "most widespread malicious program in the history of the Internet." When the user previewed the infected email or opened its attachment, Klez went to work, collecting email addresses from all over the user's hard drive. Because it spoofed email addresses, the true origin of the email was hidden. This, combined with multiple variants, kept antivirus experts on their toes. Klez was very difficult to control. In February 2003, about a year and a half after it first appeared, Klez was still ranking #1 on Sophos' frequently occurring virus list.
- 4. Storm Worm. In January 2007, the Storm Worm began to make its rounds. This worm used a natural disaster to its advantage, tempting users with the email subject line "230 dead as storm batters Europe." Once the user opened the attachment, the Storm got quiet. Users' documents didn't get deleted and their computers seemed to operate normally, but underneath the surface, Storm was doing its damage. Some recipient's computers continued to spread the virus, and others created a peer-to-peer network that could command and control other computers at its operator's will. It wasn't long before over 1.2 billion messages had been sent. According to George Dvorsky, an emerging technologies activist and blogger, 57 million messages were sent on August 22nd alone. The Storm subsided over time; Microsoft believes that an update to its Windows Malicious Software Removal Tool cleaned the worm off of over 250,000 machines by September. While the writer of the virus has yet to be caught, some suspect that it is Russian in origin and was written to facilitate the Russian Business Network's cybercrime.
- 3. MyDoom. Originally released in January of 2004, MyDoom quickly took the title of "fastest spreading virus" away from Melissa. By the end of its first day it slowed Internet traffic by 50% and was responsible for sending 1 out of every 10 emails. Only two days later, a second variant was spreading and MyDoom accounted for 20% of all email being sent over the Internet. MyDoom issued Denial of Service attacks on companies like Microsoft, AltaVista and Google. Although MyDoom was programmed to shut itself down, variants continue to emerge. The last one appeared over the weekend of July 4th in 2009, creating denial of service attacks against the White House, the Secret Service and NASDAQ.
- 2. The Love Bug. The Love Bug, also known as the Love Letter Worm and the I Love You Virus, was introduced in May 2000 and got what it wanted by using the oldest trick in the book--flattery. Subject headings for infected files were labeled "I love you." Evidentially, flattery works because in less than two weeks there were 50 million reported infections. The Love Bug caused a whopping $5.5-8.7 billion in damage and infected 10% of all computers. Onel de Guzman and Reomel Ramones were identified as the virus's creators and were arrested in the Philippines, but because writing malware wasn't against Pilipino law, they were released.
- 1. Mariposa. The Mariposa botnet was first launched in December 2008, but it wasn't noticed until May 2009. According to Panda Security, this botnet spread to more than 190 countries and compromised 13 million computers before it was shut down. Written by a 23-year-old Slovenian known as "Iserdo," Mariposa spread through an Explorer vulnerability, as well as through USB drives and MSN Messenger. After infecting computers, the botmasters could download malware and steal banking information. Parts of the botnet were rented out to third party criminals who used it as a delivery platform to commit even more cybercrime. Christopher Davis, the CEO for Defense Intelligence who first discovered the Botnet said, "It would be easier for me to provide a list of the Fortune 100 companies that weren't compromised, rather than the long list of those who were."