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A Brief History of Computer Viruses

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You need to be aware of how viruses work and infect your computer if you are to successfully protect yourself from them.


The size of the threat from viruses is staggering. 6,000 new computer viruses are created and released each month. The number is huge, and so are the threats these viruses distribute.


From making you read funny poems to paying a ransom for your files or worse - losing your banking information - there are numerous types of computer viruses of different severity. This is why we’ve created this guide - to show you what a virus is, why they’re dangerous, and how to avoid risks it poses to your internet privacy and security.


Let’s set out on a journey through the world of computer viruses. Don’t worry, we’ll be by your side to make sure you stay safe.

What is a computer virus

Let’s start with the virus definition. A computer virus is a malware capable of invading your computer to destroy its system, steal your data, or harm software. Similarly to a biological virus, a computer virus replicates itself and needs a source to spread the infection. The source is a program or file a user needs to run to infect a computer.


Computer viruses appeared half a century ago, and haven’t lost their passion for spreading chaos since.

The history of computer viruses


The first computer virus was born the same year Intel released its first commercially available microprocessor. It was created as an experiment by BBN Technologies in the US to check if it’s possible to self-replicate a program. When a virus attacked a computer, it displayed a message saying: “I’m a creeper, catch me if you can”. That’s where its name comes from - Creeper.



The mid-1970s welcomed the Rabbit virus. As you can tell from its name, this virus was very active. It self-replicated with the speed of lightning and crashed system performance just as quickly.


A year later, the first Trojan was developed called ANIMAL.



In 1982, the first PC virus was created, and not by a criminal mastermind, as you might think. No, Rich Skrenta, its creator, was a 15-year-old schoolboy at the time. The virus’s name was Elk Cloner. It was spread through a floppy disc with a game on it and attached itself to the Apple II operating system. When the game was launched for the 50th time, the screen showed this poem instead of the game:

Elk Cloner

The program with a personality
It will get on all your disks
It will infiltrate your chips
Yes, it's Cloner!

It will stick to you like glue
It will modify RAM too
Send in the Cloner!



The era of devastating viruses began in 1988. Up until then, most viruses were just jokes with funny names and messages. But things changed when the Festering Hate virus first appeared. Instead of infecting floppy disks and hard drives, it infected and destroyed every file on hard drives, memory drives, and floppy disks.



One of the most prolific viruses of the 1990s was Form, a virus responsible for more than 50% of all reported infections.


The decade also saw viruses like Leonardo and Michelangelo, whose creators were either fans of classical art or the Teenage Mutant Ninja Turtles (TMNT). The latter (Michelangelo, not TMNT) would remain unnoticed throughout the year and only activated on March 6 - Michelangelo’s birthday. So people would be advised to simply avoid using their computers on this day.


In the mid-1990s, viruses also started conquering the internet and spreading via emails and websites.



Starting in 2000, a variety of new, more dangerous viruses were developed.


An extremely successful virus back then was a sweet “love letter”. The ILOVEYOU virus was attached to an email with the subject “I love you”, allegedly sent from someone in your contact list. The virus affected over 50 million computers in less than ten days and became one of the most viral computer viruses ever.


SQL Slammer, developed in 2003, was so quick to spread, it crashed the internet less than 30 minutes after it was launched.


2007 saw the advent of the first virus capable of capturing the victim’s banking information - Zeus.



Computer viruses came up with a new distribution channel during this decade - social media. Now, clueless Facebook or Twitter users could be tricked into clicking malicious ads, suspicious links on their walls or in direct messages.


This period was one of mass infection from various computer viruses of all types.

Main ways devices get infected with viruses

So how do viruses work?


First of all, remember you can’t infect your computer by merely browsing. You need to activate a trigger - a program where the virus lives. To let it out, you need to either click on it or download it on your computer. When the virus is activated, it then infects all computers in the same network.


So it’s better not to let a virus infect your device since getting rid of it is a lot harder. Here’s how viruses spread.


Through email

Imagine you receive a real looking email from a reputable source: your bank, some official organization, or a well-known brand. Only it’s not. This is a kind of phishing email where the goal is to tempt you into downloading an attachment or opening an image.


Through infected software users download

We can’t stress this enough: don’t download anything from unreliable sources. If there’s a service you can use in a browser, do it - it’s safer than installing an unknown file you’ve downloaded from the internet. Also, pay attention to pop-up messages you see when downloading files - they may follow a malicious intent.


Through infected removable storage devices

This is how viruses first started spreading. Whether it’s a flash drive, CD or, god forbid, a floppy disc you received from someone you don’t really know, scan the content of the external device with an antivirus before running any of its files on your computer.


Through unknown links or online ads

Malvertising is an advertisement with malware inside. So with this in mind, please don’t click on the ads of brands you’ve never heard of before, familiar brands but with a strange-looking ad, or any overly shocking news stories.

How to stay safe

If we’ve made you feel like viruses are lurking in every corner of the web, trying to infect you, it’s because they are. But don’t fear: our team of Clario experts has prepared a list of tips on how best to protect your computer from viruses.

  • Use quality antivirus software. There are numerous antiviruses capable of blocking digital threats before they activate themselves (yes, Macs need an antivirus too). However, an antivirus alone can’t protect your computer from viruses, so make sure you use other security protection tools too.
  • Only download software from reliable websites. Download files from trusted manufacturer’s websites and never from unauthorized third-party providers.
  • Know the symptoms. Computer viruses are easier and faster to cure if you can detect their symptoms early on. If you start to notice strange error messages, odd system shutdowns, changes to your homepage or desktop, or slow performance, then take action and immediately scan your computer for viruses.


* * *


Those times when viruses were funny and just switched your screen upside-down are long gone. Modern viruses are designed to steal your data, preferably banking information, and use it for their own unscrupulous ends. So every internet user needs a powerful antivirus to secure their digital lives and privacy.


If you want to discover more about computer viruses and how to protect yourself, be sure to check out Clario’s blog.

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