Home » Ultimate List of Top 25 Dangerous Computer Viruses of All Time

Ultimate List of Top 25 Dangerous Computer Viruses of All Time

Want to know the most dangerous computer viruses of all time? We have made an ultimate list of top 25 those Most dangerous viruses of all time for you. These are the computer viruses that can give any computer professional big nightmares. So, it’s time for you to get alert and know about these in advance.

most dangerous computer virus

Dangerous Computer Virus #1 – Melissa

This computer virus was founded in the year 1999 and was named after a Florida dancer. The virus would come into your mail inbox as an email attachment. The moment anybody opened the email, the virus would get activated. Soon, the virus would replicate and same email message would be sent to the top 50 email addresses in the address book of your email. Surely the virus prevailed the fear of fake email messages all over.

Dangerous Computer Virus #2 – I love you

Another very deadly computer virus was the “I love you” virus. Everybody loves to hear these words, right? This virus was developed in 2000 to attack on the basis of the loveliest human emotion. A user gets an email with the subject line “I Love You”. And to express more love, there is an attachment that states “love letter for you”. If you happen to click the attachment, which everybody else would for sure, the virus would activate itself. And the same email would be sent to the top 50 people in the Windows address book. Rightly said by someone, love is surely dangerous.

Dangerous Computer Virus #3 – My Doom

This one, after being founded in 2004, created a huge wave of shocking email messages. The virus would come as an email attachment into your mail inbox. You would receive a deceiving message like “mail transaction failed”. The moment a user would click on the mail, the virus would get activated. The worm would get transferred to the address book of the mail.

Dangerous Computer Virus #4 – Storm Worm

Like the name suggests, this deadly virus hit the mail inboxes in 2006. People used to get email messages with the subject line “230 dead as storm batters Europe”. The virus used to tempt users to click the links that were supplied with viruses. As a result, PCs used to become botnet. This would allow a remote user operate the system to send spams over the Internet.

Dangerous Computer Virus #5 – CIH

This computer virus originated in the year 1998 in Taiwan. The virus destructs and corrupts your computer data after being activated. The virus infects executable files in Windows 95 and 98 systems. Once activated, the virus destroys your hard disk data and overwrites your system’s BIOS chip. You have to reprogram the BIOS chip or else you won’t be able to boot your system at all.

Dangerous Computer Virus #6 – Anna Kournikova virus

The name itself brings a lovely picture of a beautiful tennis playing woman. Well, we guys can be easily cheated on the name of a woman, right? Especially a woman like Anna Kournikova. This virus comes to your mail inbox in the form of an email message. When you open the mail, the virus gets forwarded to all the contacts present in the mail address book.

Dangerous Computer Virus #7 – Conficker virus

This virus emerged in the year 2009 and entered millions of Windows PCs to create several botnets. This gave birth to a huge army of remotely controlled computer systems, which were used to steal important financial data and other information. Many experts and anti-virus researchers called it “super bug” and “super worm” for its risky infection.

Dangerous Computer Virus #8 – Beast Trojan Horse

Developed in 2002, this computer virus infects your computer system completely after activating. Until you execute the virus, it remains safe and does no harm. But, the moment you execute, it will replicate itself and several copies will be stored in multiple directories of your computer system. Having the reverse connection capability, a remote user can access your file manager, registry editor, Webcam, power options, remote IP scanner, and many other options.

Dangerous Computer Virus #9 – Sasser Virus

 This was a dangerous virus that was formed by a 17 year old German boy. In the year 2004, the virus proved to be destructive. It hit several big names like British Coast Guard, Delta Airlines, and Agence France- Presse. Many computers got crashed in universities, corporations, and hospitals because of this deadly beast.

Dangerous Computer Virus #10 – Nimda

The virus propagated in the year 2001. Its name was derived from the word “admin” when spelled backwards. The virus spread through emails, server weak points, shared folders, and file transfers. The virus saw its rose after the famous 9/11 attack and people thought it to be a cyber-terror attack due to that.

Dangerous Computer Virus #11 – Code Red

This virus arose in the year 2001 and made use of the weakness of the indexing software in the Internet. The virus got into the servers of the white house. Another virus that came to prominence with this virus was Code Red II, which worked on the same injection vector.

Dangerous Computer Virus #12 – Bandook Rat

This virus, though similar to Beast Trojan Horse, is more destructive than the latter. Developed in 2005, this virus is a backdoor Trojan horse entering Windows operating systems mainly, such as Windows NT, XP, 2000, 2003, Vista, and 7. It is still being worked upon to make it one of the most dangerous computer viruses of all time.

Dangerous Computer Virus #13 – Sobig.F

In the year 2003, this virus attacked all the Internet gateways and email servers, causing big damage in billions of dollars. This slowed down all the global Internet access. It used to collect different email addresses from the infected computer systems. Then virus would send its multiple copies to all these addresses.

Dangerous Computer Virus #14 – SQL Slammer

Founded in 2003, this worm crashes servers and slows down Internet traffic. Now, the SQL base has nothing to do with it. This worm rather infected the servers on UDP and packed them in a single packet. As a result of which, routers could not function.

Dangerous Computer Virus #15 – Blaster

This computer worm emerged in the year 2003 and transmitted through Internet network. Soon after activating, it would show a dialog box in your system stating that you need to shut down the machine urgently.

Dangerous Computer Virus #16 – Morris

This computer virus was developed by Robert Tappan Morris, a Cornell graduate, in 1988. Initially, the virus didn’t do any harm but later it spread like crazy in several government and universities’ computers. This resulted in the crash of a lot of systems.

Dangerous Computer Virus #17 – Brain virus

Originated in the year 1986, this virus attacked the inevitable DOS operating systems. This damaged a lot of memory in several computer systems and caused them to display warning messages that the systems had been infected.

Dangerous Computer Virus #18 – Elk Cloner

Developed by Richard Skrenta, a ninth grader in the year 1982, this virus would display a poem in your computer every 50th time you would boot the machine. Way too naïve, right? Nope. The virus used to damage the floppy disk of the computer system in which it entered. Sounds easy for today’s times but in 1982 it was incredible.

Dangerous Computer Virus #19 – The Klez virus

This virus spread in the year 2001 through emails. The email would come with an Html text in the body and an attachment. The html internal frame tag would cause buggy client to automatically activate the worm. Otherwise, there would be some captivating text urging you to open the attachment, which would activate the worm, the moment you click on it.

Dangerous Computer Virus #20 – Blackworm

This computer virus spread in 2006 through emails using an external SMTP engine. Interestingly, the virus used to send itself with different subjects, body text, and attachments in emails. The most harmful thing about this virus was that it could even delete your antivirus programs if they were installed in the same directories as mentioned in the worm’s code. It could also delete the entries of these antiviruses in Windows registry, so that you could not even run the antiviruses to next time.

Dangerous Computer Virus #21 – Jerusalem

Besides being one of the first MS DOS viruses, this was one of the most dangerous computer viruses of all time. In 1987, this virus caused a lot of devastation in universities, colleges, and corporations all over. The name of the virus came from the fact that it firstly spread in Jerusalem University.

Dangerous Computer Virus #22 – Solar Sunrise

In 1998, this virus entered many computer systems of army, government, and private sector of US. The attack was named solar sunrise because of the problems that mainly took place on the computers running on Sun Solaris operating system.

Dangerous Computer Virus #23 – Bagle

Spread in the year 2004, this computer virus entered computer systems through email attachments. Moreover, things got complex when this virus created backdoors to TCP ports, which allowed a remote user to access personal and financial data from an infected system.

Dangerous Computer Virus #24 – Barrotes

This computer virus developed in the year 1993. After infecting a computer machine, it would become the resident. Every time you would start up the machine, there would be vertical lines on the monitor. At the same time, it used to get difficult for users to access their hard disk, since the virus would overwrite the master boot record of HDD.

Dangerous Computer Virus #25 – Sapphire

In the year 2003, this virus hit the big systems of continental airlines ticketing, ATMs, and 911 service. In no time, it attacked and corrupted the Internet servers.

So, this ends our list of top 25 most dangerous computer viruses of all time. We’ve tried to rank the viruses as per the damage they have done to economy and data (personal and professional). However, it’s time for you to tell us your hot favorites. Which computer viruses you think are the most destructive. Or would you like to change the ranking given above? Let’s see.

About the author

Atish Ranjan

Atish Ranjan is an established and independent voice dedicated to providing you with unique, well-researched and original information from the field of technology, SEO, social media, and blogging. He has in-depth knowledge of computers and tech as he pursued computer science.


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  • Good post for the tech lovers and computer users Atish 🙂

    Am familiar with most of the computer viruses which you’ve listed here as I’ve written the same post for my blog earlier.

    While writing that computer virus post, I feel the technology developments but I feel sad as those are using to create Malware programs.

    Anyway, to keep our system safe from these dangerous computer viruses, it is essential to have an premium anti-virus protection.

    Am using Quick heal total security latest version and it safeguards my Lappi well.

    Thanks for sharing this awesome post, keep posting these kind of stuffs for us 🙂

  • Hmm Really Nice information regarding Computer virus. If you do not care about virus then you will find a lot of problems so be careful and keep your computer away from virus by installing a good Anti virus. I Recomended best and light antivirus Microsoft Security Essentials.

  • Hello Atish,
    Well, I am always in search of a news like this. I mean it is so informative. Secondly, though these viruses are dangerous but looking at the current scenario of the people rushing towards the social web, we are becoming more apt and vulnerable to such viruses. Though many things have changed with time among which cyber security is there.
    Thanks a lot for a great list of viruses.

    Wanting to read more.

  • The best list of computer viruses I ever seen. Few names I have heard before but most of them are new for me. Great write up.

  • Amazing list of PC viruses. I didn’t know the names of any of the virus. I just heard Virus thats it. Glad that I read this post to know this. Keep writing such informative post.

  • Hi Atish,

    I’m afraid I don’t even want to know what they’re called, let alone what these nasty little things get up to – I leave all that to my anti-virus software. I think I’d have nightmares and never want to switch my computer on again if I started paying too much attention to this kind of stuff. I must say, I never knew they had such colourful names.

  • Very article Atish.
    I know some of them like Melissa, Iloveyou or mydoom cause i had them already but i’m really impressed by the rest. In addition, i have a question: do you think Y2K should be considered in this list.
    Thanks for your sharing.

  • Computer Virus will commonly happen inorder to prevent make sure to download only trusted files and use best anti virus protection software don’t ever go for free stuff.

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