There are lots of viruses. Here we listed the top worst computer viruses ever.

When we hear the word virus, we normally think of some kind of code that’s made to do any kind of harm to our computers and also spread itself to other computers.

Malicious software worms, trojans and computer viruses are on the rise as hackers, spammers and identity thieves seek new ways to steal information that can be used to empty bank accounts or spread electronic pandemonium.

Viruses are professionally created with wrong intentions in order to use your computer to attack other targets or make money by stealing information from your computer.

Different viruses affect the different system and even data servers that keep companies and the internet running.

Antivirus can only detect viruses they have ever seen. They’ve trouble in dealing with threats they’ve never seen.

There have been thousands of, millions of viruses spread online along with that they’ve caused billions of dollars of loss and damage.

All viruses are bad and harmful. But here we’ve pointed out some of the most dangerous viruses which ones were objectively worse. These are small pieces of code which completely changed the way people think about computer security.

Top 10 worst viruses ever

  1. MyDoom    

worst computer viruses ever MyDoom

via virus.wikidot

It is a computer virus which was first sighted in the year 2004 on Jan 26. It was a computer worm which normally affected Microsoft Windows PCs. This worm has a record which no other viruses have surpassed yet.

It spread through email and is the fastest spreading email worm ever. The worm simply contains a small text message “andy: I’m just doing up my job, nothing personal, sorry”.

It targeted approximately 2 million computers.

Later it was found that the developer of this worm was from Russia. But the actual developer is still unknown.


worst computer viruses ever ILOVEYOU

“ ILOVEYOU” here is nothing to do with love. This was one of the most dangerous virus ever in the history. This virus was counted as one of the most dangerous of all time as it affected tens of millions of Windows personal computers.

This attack was done in the year 2000 on May 5  at a local time in the Philippines. This virus is called as ILOVEYOU as the subject line of this virus was ILOVEYOU and the attachment was a text file “LOVE-LETTER-FOR-YOU.txt.vbs“.

This virus reached to 45 million computers in just two days and caused a damage of about $10 billion after the attack.

It also affected many banking systems. Basically, it entered through email and once the file is downloaded, it crashes the entire system along with the server connected to it.

  1. Melissa Virus

worst computer viruses ever melissa-virus

This virus is also counted as among the most dangerous virus of all time. Melissa Virus is a type of mass mailing macro virus. This virus was developed in the year 1999 on March 26. This virus basically overloads the victim’s network.

Within just a few days, Melissa spread to thousands of computers. Melissa didn’t damage any computer by themselves. But it slowed down the email service and caused a loss of about $80  million to the company.

Many antivirus professionals and IT experts tried to stop this virus by blocking the emails and reaching to people’s inbox.

The man behind this virus was David L Smith, who was immediately caught after a week Melissa was released. He was kept in prison for 20 months and was fined $5000.

  1. WannaCry Ransomware Virus

worst computer viruses ever wannacry

via wikipedia

This is the latest and also considered as one of the most dangerous virus. This virus came into existence in May 2017 and almost the entire world was affected by this virus.

Even you may have heard about this virus. Wannacry basically enters the victim’s computer through email or any other third-party software. This virus targeted computers that run Microsoft Windows as their Operating System.

WannaCry encrypts the victim’s computer and demands for ransom payments. The payments were taken in Bitcoin Cryptocurrency. This virus affected many banks and organizations across the world.

The approximation estimated to have affected by the virus was more than 200,000 computers across 150 countries. There was total damage of billions of dollars.

  1. Code Red Worm

worst computer viruses ever code red virus

Code Red is a worm which was released in 2001 and attacked computers using Windows 2000. This worm basically attacked Microsoft’s IIS web server and crashed the entire server. More than 20 lakh computers were affected by this virus. It caused a loss of $2 billion.

This worm also initiated a DDos attack on the White House leading to overloading to all the machines in the white house. Later, eEye Digital Security identified this worm.

  1. Nimda

worst computer viruses ever nimda virus

via emaze

Nimda is a type of worm which quickly spreads to many computers. This worm first released on September 18, 2001. This worm was released exactly 1 week after the attack of the world trade center and Pentagon.

Nimda normally affected tomputers with Microsoft Windows as the Operating System. The main priority of this worm was to attack the internet servers and to destroy internet traffic through emails.  

  1. Sql slammer

worst computer viruses ever sql slammer

Another new virus appeared in the year 2003 which quickly spread to the internet within just a few minutes after infecting the first internet server.

It is actually a worm which caused a Denial of Service(DOS) resulting to slow down the entire Internet traffic with just a few minutes. Thi worm was doubling its number of victims every second.

It caused billions of dollars lost by crashing Bank of Americas ATM network, the city of Seattle’s 911 and also Continental Airlines electronic ticket system.

This worm spread so rapidly that it infected 75,000 victims within just 10 minutes.  

  1. CryptoLocker

worst computer viruses ever crypto-locker

CryptoLocker was a ransomware attack which means that it is programmed to block access to files or computer of the victim until a sum of money is paid. This attack occurs from  5 September 2013 to late May 2014.

CryptoLocker targeted computers using Microsoft Windows as their Operating System. It came through email attachments and when a file was activated it would encrypt any files of the victim.

Cryptolocker also could jump into another network the victim’s server is connected.

The attacker only decrypts the victim’s computer after paying an amount of $400. CryptoLocker extorted a sum in excess of about $3 million before it was brought into a halt in 2004.

  1. Storm Worm

worst computer viruses ever storm-worm

via wikipedia

Storm Worm was discovered on 2007 January 17. This worm was also spread through emails. The name Storm Worm is from the subject of the email which read ‘’230 dead as storm batters Europe’’.

Storm Worm at its peak accounted for 8% of all malware-infected globally. It was basically a Trojan Horse program which had many versions.

Some of them turn computers into BOTS or zombies and would be used to send further spam mail across the internet. 

  1. Mebroot

worst computer viruses ever mebroot

via pixabay

Mebroot is also called as a Torpig which uses spying technique known as the man-in-the-browser. It was a trojan horse which used different techniques to control the victim’s computer.

Mebroot also tries to steal information, using fake websites that look and behave exactly like the original website.

By 2008, Torpig managed to steal information connected to 500,000 bank accounts. But still, the people behind this was not caught.

Even though many other attacks occurred in the history. These were the top main viruses or computer attacks of all time.



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