computer virus

8 Most Worst Computer Viruses in Computer History

Globally computer virus has been one of the most disturbing influences on our computer systems. These computer viruses are malicious code designed to read, write and erase computer data.

When such malicious pieces of code enter your computer they are capable of causing a world of problems for your systems and yourself.

What steps can be taken to avoid these viruses?

As the user, you are armed with the capability to track down and erase all occurrences of the virus, or a simpler method is to format everything and start fresh.

But the catch is that in both of these cases there will be the loss of time and data, potentially. These viruses have the capability of transferring the data from your computer to another, essentially violating your privacy.

The founder of this discovery was Fred Cohen who identified a computer virus and defined it as a self-replicating program, designed to adversely modify our systems as a virus. Ever since such infection is called a virus.


It is the computer worm that attacked more than ten millions of Windows personal computers.

The way this virus works is to send us an email message which includes a subject line “ILOVEYOU” and has the attachment of “LOVE-LETTER-FOR-YOU.txt.vbs.”

Once clicked, it had the capabilities of forwarding itself to everybody in the victim’s address book and proceed to overwrite files with itself which makes the computer unbootable.

Two Filipino Programers- Reonel Ramones, and Onel de Guzman created this virus.

Morris Worm

This virus is named after its creator Robert Tappan Morris who came up with this is 1988, a graduate student of Cornell University released the virus which affected approximately 10% of all the computers that were being connected to the internet.

At that time 60,000 computers were attached to the internet, and the worm infected 10% of them. The unique feature of this virus to hit on the speed of the computer as it slows down the computer speed till the point at which it becomes unworkable.


Another example of a nasty computer virus is Conficker which was created to majorly targets Microsoft Windows Operating system.

This virus was first identified in November 2008. The strategy of this virus is to use the flaws of the Windows operating system to fetch the administrator password via dictionary attacks while forming a botnet.

This virus had a wider reach in which it infected millions of computers which comprised of government, business and home computer in over 190 countries.

The word “Computer Virus” itself is a scary name for most of the computer users. Because we all know, that viruses can bring in a lot of damage to the computer.

This danger virus enters and harm the victim’s privacy, get access to personal and private files and can even corrupt the precious data which includes photos, videos, saved passwords, etc.

This computer virus has caused huge financial losses for many companies.


This virus wand phishing as first discovered in 2007, this is a type of Trojan horse malware that targets mainly drive-by downloads schemes.

It was majorly used to gather and steal information from the United States Department of Transportation. Zeus virus is a very dangerous computer virus because it possesses special sly computer infecting techniques that make it challenging for any antivirus to detect it.

Due to its infectious and widespread reach technologies, this malware has become one of the largest botnets on the Internet.

My doom

On one of the most fateful day of 1st February 2004, almost one million computers were infected with Mydoom’s denial of service attacks, and it is one of the largest such attacks to the date.

The Modus operandi of this virus is that it spreads through email which contains a text message which says “Andy; I’m just doing my job, nothing personal, sorry.” When the victim receives and opens this email the already present malicious code starts automatically downloading and then steal the victim’s entire contacts of email, from here it spread to the victim’s friend, relatives, and colleagues.

My Doom was another virus, a worm to be exact, which arrived in 2004. It became another fast-spreading email virus, much like ILOVEYOU.

My Doom was able to infect two million computers and created a massive denial of service attack that adversely affects the whole world wide web.

It replicated by sending itself via email. It fooled people into clicking on it by using the subject line “Mail Transaction Failed”, and it would send itself out using the email address book of the user.

The damages of this virus were said to be in the range of $38 billion.

SQL Slammer

As the name suggests this virus as a wider reach, SQL Slammer is a computer worm that infected 75,000 victims within ten minutes.

SQL Slammer once into the infected computer showed drastic results when it slowed down the internet speed and traffic and a good example of it was that it brought down South Korea’s online web traffic to a standstill for 12 hours.

SQL Slammer mainly targeted on the servers by generating random IP addresses and discharging the worm to those IP addresses.

This virus worked by affecting servers, not computers. Compared to other viruses, this one was very small, no larger than 380 bytes.

The method that this virus used to spread itself was to generate random IP addresses and sending itself to these IP addresses.

If the IP address belonged to a computer system that ran Microsoft’s SQL Server Desktop Engine (unpatched version), then that computer would become infected and send itself out to more random IP addresses. This virus was able to infect over 75,000 computers in less than 10 minutes.

It created so much unwanted traffic that it overloaded thousands of network routers across the world, which eventually led to shutdowns.


This virus was named after an exotic dancer from Florida, and it was created in 1999 by David Smith; it was a Microsoft Word macro.

It worked by spreading itself through email. The virus would arrive in peoples Inbox with the subject title “here is the document you asked for, don’t show it to anybody else”.

This was, of course, designed to goad people into clicking on it, and for those who did, the virus would immediately forward itself to all the people in the user’s address book.

After some time, the virus was able to replicate itself across a large portion of the web.

Though it didn’t adversely affect the internet, it did cause a big problem for many email services, as it increased traffic tenfold; this ultimately led to email services running considerably slower.

David Smith was eventually arrested and sent to jail for 20 months, he was also fined $5000 by the US government. Though it didn’t cause any real damage to any systems, it was one of the first viruses to gain any sort of recognition.

The Klez Virus

With the natural progression and advancements in our technology, new viruses have been developed and pushed out there; one of such viruses, known to quite a number of people is the Klez Virus.

It first arrived on the scene in 2001, and its unique characteristics lead to it floating around the internet for several months. The Klez Virus successfully replicated itself via email services.

There were numerous versions of it; all made its behavior either like a Trojan, worm or virus. As a virus, it was capable of disabling the internet security software on an end users computer and act as a fake antivirus removal tool itself.

When the virus came out, there were many new versions that were released shortly after, these updated versions were capable of spoofing. It was also capable of deleting email messages and rendering a computer system inoperable.

How Can ITL Help?

  1. Install Anti-Virus/Malware Software

This protection is a must-have first step in keeping your computer virus-free. ITL is the best software which every computer should install.

  1. Keep Your Anti-Virus Software Up to Date

ITL has an automatic scanner which updates the computer and helps in maintaining and cleaning the machine. You may find free anti-virus software is better if nothing else works, but keep in mind that it’s not the best solution.

  1. Secure Your Network

The most commonly used method that the computer gets infects is due to external paraphilia’s, as our computers connect to our files, printers, or the Internet via a Wi-Fi connection secure it with a password to give access to only a closed group and that the password is secure.

Never leave your WIFI unattended and stop the broadcast an open Wi-Fi connection. If you have guests who use your Internet, allow your guest SSID that has a different password, to protect it from cyber hackers who can have evil and harmful intention.

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