6 Most Dangerous Viruses Of All Time

Most Dangerous Viruses Of All Time

Computers viruses affect tens of thousands of computers worldwide each year leading to large expenses, identify theft, and stolen information which can be hard to get back. While many computer viruses aren't that dangerous and can be removed quite easily, there’s some however that take dangerous to a whole new level. This expert guide will give your insight into the most dangerous computer viruses of all time that did major damage to the computer industry.

#1 The ILOVEYOU Virus


First created by, Reonel Ramones and Onel de Guzman, two Filipino programmers, the ILOVEYOU Virus was considered the most dangerous of all viruses. The damages of this virus went into an excess of $10 billion. This virus affected 10% of the world's computers who were connected to the internet. It was that bad that large corporations and government agencies had to take their mailing systems offline to prevent their systems from being infected.

The way this virus worked was through social engineering. It made people click on an attachment or love confession, and inside this attachment was a script which posed as a TXT file. When it was clicked upon, it sent itself to the people who were connected with the user's mailing list. When sent it started to overwrite files causing computers to become unbootable. Unfortunately, the pair wasn't charged because there wasn't a law against malware at this time.

#2 Melissa


Created in 1999 by David L Smith, the virus was named Melissa after an exotic Florida dancer. This virus began as a word document which was infected and posted on the alt.sex usenet group. It claimed to be a list of pornographic site passwords for people to use. As curiosity grew, it caused people to download and open it which would trigger the macro inside. The macro would be unleashed and would send itself to the top 50 people in the computer user's email address book. This virus disrupted email services, increased email traffic, and corrupted some documents by inserting a reference to the Simpsons in them. He was caught, fined and caused $80 million in overall damages.

#3 Zeus


Designed to infect Windows computers, Zeus was a Trojan horse which was designed to make those computers perform illegal and criminal tasks. The most common criminal tasks it was sent out to do was to form grab and man-in-the-browser keylog. Most computers were infected through phishing scams and downloads. First found in 2009, this virus managed to compromise thousands of computers and FTP accounts from large banks and multinational corporations like Bank of America, Oracle, Amazon, and Cisco. Botnets of this virus stole banking accounts, email accounts, and social network login credentials. Over 1 million computers were estimated to be infected with $70 million being stolen.  

#4 Code Red

Code Red

First appearing in 2001, Code red was discovered by two employees of eEye Digital Security. The Code Red virus was targeted to affect Microsoft web server installed computers. When infected the virus exploited an overflow problem with the buffer in the computer system. Because it leaves minor traces, it was able to duplicate itself more and more until it takes over a lot of the computer resources. Once duplicated many times it then launched on several IP addresses a denial of service attack. Once an infection has occurred it left a message of 'Hacked By Chinese!'. It was estimated to cost $2 billion in damages, with 1-2milliion affected servers.

#5 Sasser


First discovered in 2004 this computer virus was created by a science student by the name of Sven Jaschan. Sasser was an annoying and fast moving virus which crashed computers and slowed them down. It reportedly affected millions of computers worldwide and it infected critical infrastructure. It took advantage of vulnerabilities in the buffer overflow in LSASS or Local Security Authority Subsystem Service which controlled local account security policies. This caused the computer to crash. It also affected other computers automatically through system resources that connect other internet machines. Damage was estimated to be $18 billion and it caused over a million computers to be infected with airlines, public transport, hospitals and another critical infrastructure being targeted.

#6 Conficker


Conficker, also known as Downadup, was a worm virus which worked on and exploited the vulnerability of network services. When infection occurred it would reset lockout policies of accounts, block Windows upgrade access to antivirus sites, and turn off certain services. It would then start to install software which would turn computers into botnet slaves and scam users out of lots of money.


Computer viruses are dangerous in themselves, but seeing how dangerous they really are from these most dangerous viruses you can see why many people are affected when they’re released. Have you been a victim of a computer virus?

Authored By Bill M

With over 30 years in the IT industry, Bill M has helped many people overcome their IT problems by providing effective problem-solving solutions. Bill is an IT consultant who initially started out as a computer programmer within the finance industry maintaining and developing large applications. Across his time working in these industries, Bill began to devise new ways to get better results for his customers. This lead him to become fully qualified in IT Service Management. He currently holds an ITIL Expert (V3) qualification. Today Bill is the owner of a Jim's Computer Services franchise in Drouin. He works with small to medium businesses so they can get the most out of their technology, what they want to achieve, and what they own in today’s world. His aim is to help all businesses gain value from all technologies that are available to them for maximum results.

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