Exploring Different Types Of Computer Malware: Viruses

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A computer virus is any type of malicious code that needs some type of user interaction in order to be installed and replicated. This is the key point you want to remember. Computer viruses need the user to actually perform some kind of action in order for them to install and replicate. For example, a user connects his computer to an infected computer and downloads an application or clicks on an executable file. Once the virus gets installed on his computer it can then turn around and infect other computers. Viruses can spread very quickly if left unchecked.

Famous computer viruses you may (or may not) have heard about


MyDoom was an email-based computer virus that spread very quickly and hit both Google and Microsoft with a Distributed Denial of Service (DDoS) attack. MyDoom infected somewhere between 16-25% of emails in 2004 with a damage bill that reached $38 billion. Not a small chunk of change.


With Stuxnet we’re deep into cyberwar territory. Stuxnet spread via USB thumb drives and targeted the uranium enrichment plant in Natanz, Iran causing its centrifuges to self-destruct. What’s interesting to note about Stuxnet is that its ultimate target wasn’t the computer itself but a piece of physical equipment the computer was controlling. It was all about the centrifuges.

Nobody knows how much Stuxnet cost the Iranian government. However, you can bet that it cost them a pretty penny and set their nuclear ambitions back years. Wired has an interesting article about how it all went down.


Cryptolocker, a type of virus commonly referred to as ransomware, popped up in 2013 and rapidly spread via email attachments. The victim’s files were encrypted and the ransom amount ranged from $200 to around $2000. Victims who paid it received a key that decrypted, or “freed”, their files.

Cryptolocker managed to snare about half a million PCs and made close to $30 million dollars in just 100 days. Some users were able to save their files because they had been backing them up regularly. You can learn how to backup your files using Windows 10 File History and System Image.


Way back in 2000 people weren’t as savvy as they are now about the link between strange emails and computer viruses. The ILOVEYOU virus started with an innocuous looking email with “I love you” in the subject line. A bunch of naive people clicked on it and then clicked one more time (aargh!) on an email attachment named “LOVE-LETTER-FOR-YOU.TXT.vbs”. The virus then overwrote both their personal and system files. The virus spread far and wide before it was finally put down. The cost in damages from the ILOVEYOU computer virus is estimated to be somewhere around $15 billion.

Storm Worm

In 2006, people started receiving an email with the compelling subject line, 230 dead as storm batters Europe”. Unfortunately, anyone who clicked on the link to the fake news story ended up with a computer infected with the Storm Worm virus. Nobody really knows the total amount of financial damage from the fake news computer virus. However, it’s estimated that about 200 million emails were sent.

Computer viruses can spread very fast, sometimes causing billions of dollars worth of damage in just 24 hours. Take them very seriously.

For more information on malware see:

Exploring Different Types Of Computer Malware: Rootkits & Keyloggers

Exploring Different Types Of Computer Malware: Trojans

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