You receive an email titled "ILOVEYOU". Inside, a supposed love letter. Naturally, you click.
Bad idea.
In May 2000, millions of internet users did exactly the same thing and unwittingly participated in one of the biggest computer epidemics in history.
Since then, these little critters have evolved considerably. They no longer simply crash Windows or send emails to everyone in your address book. Some encrypt your files, steal your passwords, turn your webcam into a weapon in a digital army, or even sell access to your computer to other cybercriminals. In short, it's become quite professional.
Here are 12 viruses and malware that have particularly left their mark on the internet, from good old Word macros to data thieves. Passwords much more discreet than those we currently encounter.
A quick note for the purists: not everything that follows is technically a "virus." It also contains worms, trojansransomware, botnets, and infostealers. But in real life, we often still call all of that computer viruses. So let's not quibble too much.
From infected attachments to zombie PCs
1. Melissa – 1999
Melissa had nothing particularly spectacular to look at. No flashing screen, no big "YOU HAVE BEEN HACKED" message. The virus was simply hiding in a Word document.
Once the file was open and the macro run, Melissa used Outlook to send the same document to the first 50 contacts in her address book. These people then received a message from someone they knew. Naturally, that inspires confidence.
The spread was significant enough to overwhelm the email servers of numerous businesses and government agencies. The FBI estimates that approximately one million email accounts were affected.
Melissa had just demonstrated something that pirates still use very well: rather than trying to force a door, it's better to politely ask someone to open it.
2. ILOVEYOU – 2000
A year later, the creators of ILOVEYOU perfected the method.
This time, the email outright promised a declaration of love. attachment The letter "LOVE-LETTER-FOR-YOU" obviously contained something else.
Once launched under Windows, it could modify files and then send a copy of the message to contacts saved on the computer. And it worked. Very, very well.
ILOVEYOU spread at breakneck speed across the world. It's hard to find a better example to understand the principle of social engineering: technically, the most interesting vulnerability was located between the chair and the keyboard.
3. Code Red – 2001
Code Red changed the recipe a bit since it no longer even needed to wait for someone to open an attachment.
This worm searched on the Internet It could target vulnerable Microsoft IIS servers and automatically infect them. Once installed, it would continue searching for new victims and could participate in denial-of-service attacks.
That's one of the great rules of cybersecurity: when a publisher releases an important security patch, clicking "Remind me later" three times isn't necessarily the best strategy.
4. SQL Slammer – 2003
SQL Slammer was tiny. Just a few hundred bytes. But clearly, size isn't everything.
In January 2003, this worm targeting Microsoft SQL Server and MSDE spread extremely rapidly across the Internet. It constantly searched for new vulnerable machines, generating enormous amounts of traffic in the process.
Result: slowed networks, disrupted services, and system administrators probably having a very bad day.
The most frustrating thing about this whole story is that a patch to block the vulnerability had been available for several months. Yes, that old story again. updates.
5. MyDoom – 2004
MyDoom also arrived by email, with its small infected attachment.
Once installed, it retrieved addresses from the computer to continue spreading. But most importantly, infected machines could be used remotely in coordinated attacks.
This is where the concept of the "zombie" PC really starts to emerge. Your computer appears to be working normally, except that in the back of the room it has discreetly joined an army.
Vibe.
6. Conficker – 2008
Conficker is probably one of the last really great computer worms of that era.
It exploited a vulnerability in Windows, but could also take advantage of administrator passwords that were a little too easy to guess and move from one machine to another on a network or via certain removable media.
Microsoft estimates that between 9 and 15 million computers may have been infected at its peak.
Conficker could also block access to certain security tools and services, just to make things a little more difficult for those trying to get rid of it. Nice one, right to the end.
Then malware became a real business
After Conficker, major infections obviously did not disappear. But their objective gradually changed.
Crashing computers is fun for five minutes. Making money from it is immediately more interesting.
7. Emotet – from 2014
Emotet is a good example of this evolution.
Initially, it was primarily a banking Trojan. Then the malware evolved into a veritable gateway for other cybercriminal groups.
An infected machine could then receive other malwareincluding ransomware.
In other words, it's no longer enough to simply hack your computer; you can also resell access to it. Malware becomes a service. Hacking becomes a business. And everyone's happy, except, of course, the person who owns the computer.
8. Mirai – 2016
Mirai had another good idea: why limit themselves to PCs?
The malware searched the internet for poorly protected connected devices, particularly cameras and routers still using their default usernames and passwords. Once infected, these devices joined a botnet.
In 2016, Mirai notably participated in a massive attack against the DNS provider Dyn. Several well-known services then became temporarily difficult or impossible to access.
And all this thanks, among other things, to connected cameras whose password no one had changed.
If you have suddenly thought of a connected device at home configured with "admin/admin", it might be time to go and take a look.
9. WannaCry – 2017
WannaCry lives up to its name.
In May 2017, this ransomware spread across more than 150 countries and affected hundreds of thousands of machines.
Its operation was particularly vicious: it could automatically switch from one vulnerable Windows computer to another before encrypting the files on the machine and demanding a ransom.
Businesses, government agencies, and hospitals were affected. And, once again, the Windows vulnerability exploited by WannaCry already had a patch.
I warned you that this update issue would come back.
10. NotPetya – 2017
Barely time to digest WannaCry before NotPetya arrived a few weeks later.
At first glance, it might have looked like a new ransomware. Except that recovering your files after paying wasn't exactly part of the plan.
The software was primarily destructive.
The attack initially affected Ukraine before spreading to major international companies. Some saw thousands of machines rendered unusable.
NotPetya has perfectly demonstrated that a cyberattack originating from a specific piece of software or network can quickly turn into a global catastrophe.
11. LockBit – from 2019
With LockBit, we are almost moving to the industrial stage.
The group used the "Ransomware-as-a-Service," or RaaS, model. To simplify greatly: some develop the ransomware and its infrastructure, while others are responsible for finding and attacking victims. The profits are then shared.
A sort of ransomware franchise, but much less friendly.
LockBit became one of the biggest names in the industry before an international operation in 2024 allowed law enforcement to take control of part of its infrastructure.
But this operation shows precisely how much the model has changed: we are no longer simply hunting a virus. We are attacking a real organization.
12. Lumma Stealer – from 2022
And then there are the much less spectacular malware attacks.
Lumma Stealer doesn't necessarily try to lock your screen or proudly announce that it has just hacked your computer. It prefers to search discreetly.
Passwords saved in the browser, session cookies, banking information, cryptocurrency data… anything that might have value interests him.
Microsoft observed hundreds of thousands of infected Windows machines ahead of a major operation against its infrastructure in 2025.
The problem with this kind of malware is precisely that it has no interest in attracting attention. If someone has just stolen your keys, they're generally not going to ring the doorbell to let you know.
And what about current computer viruses?
If you were expecting a major global virus today, with a funny name and a blue screen of death, you may be disappointed.
The threat has become much more fragmented.
The latest overview from the European agency ENISA continues to rank ransomware among the incidents with the greatest short-term impact. Phishing and other social engineering techniques also remain prevalent, as does the exploitation of security vulnerabilities. The agency also observes an increasing use of artificial intelligence to facilitate certain malicious operations.
But these are in particular the infostealers which clearly illustrate the current threat.
Lumma is just one example. In June 2026, Microsoft, Europol, and several partners conducted an operation against the infrastructure used by StealC and AmadeyMore than 200 domains and IP addresses Malicious actors linked to these services had been identified.
StealC can, among other things, retrieve passwords, cookies, browser dataCrypto wallets or information from certain applications. The stolen data can then be resold and used to access other accounts or networks.
And the techniques used to get you to install this junk have also evolved.
Of course, you can still find the good old fraudulent emails, but also fake software, tricked search results, malicious ads, or the "ClickFix" technique. This technique involves, for example, displaying a fake problem or a fake CAPTCHA and then asking the user to copy and paste a command onto their computer themselves.
Yes, the malware now sometimes asks you to install it yourself.
You had to think about it.
Ultimately, good habits haven't changed all that much.
Malware has evolved a lot since Melissa and ILOVEYOU, but the methods to make life difficult for them remain fairly basic.
Update your software. Use different and strong passwords. Enable two-factor authentication whenever possible. Also, keep a backup of files that are truly important to you.
And above all, be wary when someone asks you to open an attachment, download a program, or copy a strange command into Windows.
Byothe explains how manage your passwords properly on the Internet and how check that a file is safe before downloading it.
Because ultimately, despite nearly thirty years of evolution in computer viruses, cybercriminals still exploit two particularly effective vulnerabilities: software that is not updated…
…and us.
