The Anna Kournikova virus got its name for a reason - recipients thought they were downloading photos of a sexy tennis player. The financial damage from the virus was not the most significant, but the virus became very popular in popular culture, in particular it was mentioned in one of the episodes of the 2002 TV series Friends.
2. Sasser (2004)
In April 2004, Microsoft released a patch for the LSASS (Local Security Authentication Server) system service. A little later, a German teenager released the Sasser worm, which exploited this vulnerability on unpatched machines. Numerous variations of Sasser have appeared in the networks of airlines, transportation companies and healthcare providers, causing $18 billion in damage.
3. Melissa (1999)
Named after a Florida stripper, the Melissa virus was designed to spread by sending malicious code to the top 50 contacts in a victim's Microsoft Outlook address book. The attack was so successful that the virus infected 20 percent of computers worldwide and caused $80 million in damage.
The creator of the virus, David L. Smith, was arrested by the FBI, spent 20 months in prison and paid a $5,000 fine.
While most of the malware on our list caused trouble, Zeus (aka Zbot) was originally a tool used by an organized crime group.
The Trojan used phishing and keylogging techniques to steal bank accounts from victims. The malware successfully stole $70 million from victims' accounts.
5. Storm Trojan (2007)
Storm Trojan has become one of the fastest-spreading threats, as within three days of its release in January 2007, it reached an 8 percent infection rate on computers worldwide.
The Trojan created a massive botnet of 1 to 10 million computers, and due to its architecture of changing code every 10 minutes, Storm Trojan turned out to be a very persistent malware.
The ILOVEYOU (Chain Letter) worm disguised itself as a text file from a fan.
In fact, the love letter was a serious threat: in May 2000, the threat spread to 10 percent of networked computers, forcing the CIA to shut down its servers to prevent further spread. Damage is estimated at $15 billion.
7. Sircam (2001)
Like many early malicious scripts, Sircam used social engineering techniques to trick users into opening an email attachment.
The worm used random Microsoft Office files on the victim's computer, infected them and sent malicious code to address book contacts. Sircam caused $3 billion in damage, according to a University of Florida study.
8. Nimda (2001)
Released after the attacks of September 11, 2001, the Nimda worm was widely believed to have links to al-Qaeda, but this was never proven, and even Attorney General John Ashcroft denied any connection to the terrorist organization.
The threat spread through multiple vectors and brought down banking networks, federal court networks, and other computer networks. Cleanup costs for Nimda exceeded $500 million in the first few days.
At just 376 bytes, the SQL Slammer worm packed a lot of destruction into a compact package. The worm shut down the Internet, emergency call centers, 12,000 Bank of America ATMs and knocked out much of South Korea from the Internet. The worm was also able to disable access to the World Wide Web at a nuclear power plant in Ohio.
10. Michaelangelo (1992)
The Michaelangelo virus spread to a relatively small number of computers and caused little actual damage. However, the concept of a virus to “blow up a computer” on March 6, 1992 caused mass hysteria among users, which was repeated every year on this date.
11. Code Red (2001)
The Code Red worm, named after a variety of Mountain Dew, infected a third of Microsoft's IIS web servers upon release.
He was able to disrupt the whitehouse.gov website by replacing the main page with the message “Hacked by Chinese!” The damage caused by Code Red worldwide is estimated at billions of dollars.
12. Cryptolocker (2014)
Computers infected with Cryptolocker encrypted important files and demanded a ransom. Users who paid the hackers more than $300 million in Bitcoin received access to the encryption key, while others lost access to the files forever.
The Sobig.F Trojan infected more than 2 million computers in 2003, crippling Air Canada and causing slowdowns in computer networks around the world. The malware resulted in $37.1 billion in cleanup costs, one of the most expensive remediation campaigns of all time.
14. Skulls.A (2004)
Skulls.A (2004) is a mobile Trojan that infected Nokia 7610 and other SymbOS devices. The malware was designed to change all icons on infected smartphones to the Jolly Roger icon and disable all smartphone functions except making and receiving calls.
According to F-Secure, Skulls.A caused minor damage, but the Trojan was insidious.
15. Stuxnet (2009)
Stuxnet is one of the most famous viruses created for cyber warfare. Created as part of a joint effort between Israel and the United States, Stuxnet targeted uranium enrichment systems in Iran.
Infected computers controlled the centrifuges until they were physically destroyed, and informed the operator that all operations were proceeding as normal.
In April 2004, MyDoom was named “the worst infection of all time” by TechRepublic, for good reason. The worm increased page load times by 50 percent, blocked infected computers from accessing antivirus software sites and launched attacks on computer giant Microsoft, causing service failures.
The MyDoom cleanup campaign cost $40 billion.
17. Netsky (2004)
The Netsky worm, created by the same teenager who developed Sasser, traveled around the world via email attachments. The P version of Netsky was the most widespread worm in the world two years after its launch in February 2004.
18. Conficker (2008)
The Conficker worm (also known as Downup, Downadup, Kido) was first discovered in 2008 and was designed to disable antivirus programs on infected computers and block automatic updates that could remove the threat.
Conficker quickly spread across numerous networks, including defense networks in the UK, France and Germany, causing $9 billion in damage.
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