The 10 worst computer viruses in history

Computer virus: those two words instantly make us sweat, and for good reason. Since the 1980s, viruses have wreaked havoc on everything from our inboxes to industrial facilities. As cybersecurity has improved, the damage wrought by viruses throughout history reminds us of what these bugs can do.

Imagine: the year is 1986 and you see a message on your Windows PC indicating that your computer is infected with a virus. To remedy the situation, you are responsible for calling the Basit brothers and Amjad Farooq Alvi. At that point, as you pick up your phone and start dialing, you immediately regret hacking the brothers software (as it should).

The virus was known as Brain, the first PC virus. It was technically built for software protection. However, the good intentions did not last. Soon, viruses were malicious in nature, causing billions of dollars in damage, identity theft, damaged hardware…the list goes on.

Millions of viruses have existed since Brain in 1986. However, some have been far worse than others.

Melissa – 1999

In 1999, computer viruses were still a relatively new concept. However, the Melissa virus, known as the fastest growing virus at the time, quickly highlighted them as a growing concern for everyone.

It all started when a man named David Lee Smith used an AOL account to download a file from the Internet that, when downloaded, hijacked early versions of Microsoft Word. If a user also had Microsoft Outlook, the virus emailed itself to the first 50 people in a user's address book.

Although it might not seem so bad, it was. According to the FBI, many corporate and government mail servers were overloaded and had to be shut down. Additionally, Internet traffic has slowed to a trickle.

This virus did have a happy ending. A few months after David Lee Smith was convicted of his crime, the FBI developed its Cyber ​​Division, which still investigates cybercrime to this day.

ILOVEYOU – 2000

Who doesn't want to find a love letter in their inbox? Unfortunately, many Romeos and Juliets in 2000 fell victim to a virus after clicking on what looked like a love letter in Microsoft Outlook.

The virus ILOVEYOU (known as Love Bug at the time) was technically a worm and started out as a seemingly innocent email. The subject line, " ILOVEYOU,” prompted email users to click. Inside, a text file titled “LOVE-LETTER-FOR-YOU.TXT.VBS” was waiting.

Once the text file was opened, the worm permanently damaged files such as photos and critical documents on a user's computer. Worse still, it would attach itself to all Microsoft Outlook addresses, spreading like wildfire.

As a worm, no further human intervention was needed to maintain ILOVEYOU in motion. As a result, millions of computers were infected in just a few days.

Code Red – 2001

One of the most disturbing viruses on our list, Code Red took over corporate computing in 2001. In fact, it is considered by many to be the first serious attack on a corporate system.

The Code Red worm specifically targeted systems running Microsoft Internet Information Services (IIS) for Windows Server. As described in a Microsoft security bulletin, the attacker could use an unchecked buffer, establish a server session, perform a buffer overflow, and execute code on the web server.

The result? Important websites would display "Welcome to http://www.worm.com!" Hacked by Chinese! and nothing else. The worm has also been the source of various dangerous Denial of Service (DoS) attacks.

But this name that sounds ominous? He was inspired by the drink the security people were sipping when they found the worm: Mountain Dew Code Red.

Nimda – 2001

Nimda hit just months after Code Red and shortly after the shocking 11/XNUMX attacks. As a worm, Nimda was similar to ILOVEYOU and Code Red in that it reproduced.

However, Nimda was particularly damaging because it could be spread in a variety of ways, including via email and through compromised websites. Nimda affected Windows operating systems and was able to modify system files and even create guest accounts.

Because of Nimda, millions of machines were infected and many large companies had to shut down their networks and operations. The true cost of Nimda has yet to be fully estimated. But trust us when we say it's beaucoup.

Sobig – 2003

Although opening an email does not lead to an infection, email attachments are a whole different Pandora's box (pun intended). Opening weird attachments from email addresses you don't recognize is a big no-no. And although many email users know this today, things were different in 2003.

The Sobig worm has infected millions of Microsoft computers via email. The threat would arrive in your inbox with a subject line like "Details" or "Thanks!" And inside there would be an attachment that just needed a click.

When clicked, Sobig infects the computer, searches for other email addresses in various computer files, and then quickly replicates itself by sending itself to those addresses.

Worse still, Sobig had several variants, including A, B, C, D, E, and F. The "F" variant was by far the worst of the bunch. In August 2003, it was reported that one in 17 emails was a copy of the Sobig.F virus.

Due to its spreading abilities, Sobig has overwhelmed networks around the world and caused billions of dollars in damage.

Mydoom – 2004

“Just doing my job, nothing personal, sorry. »

That was the message sent by the Mydoom email worm, first discovered in 2004. And a job it did, indeed. Mydoom quickly became the fastest growing email worm in history. In fact, he still holds the title.

Similar to Sobig and other worms on this list, Mydoom spread primarily through email attachments. If the attachment was opened, the worm would send itself to other email addresses found in the user's address book or other local files.

The rapid growth of Mydoom has slowed internet traffic around the world. At the time, it was reported that some websites were experiencing response times that were 8-10% lower than average. Mydoom was also behind several DoS and DDoS attacks, including attacks against the United States and South Korea.

Zeus – 2007

Zeus, also known as Zbot, is a Trojan that infects Microsoft Windows. The malware most often targets financial or banking information. The first sighting of Zeus dates back to 2007, when the malware was discovered stealing information from the US Department of Transportation.

Zeus works by developing a botnet, which is a network of remote-controlled computers or bots that have been infected with malware. Therefore, an attacker can control several computers at the same time. Zeus often infects a computer after a user clicks on a malicious link in an email or downloads an infected file.

Why is Zeus so dangerous? For example, malware can use keylogging to capture sensitive information such as online banking passwords. In fact, in 2010 the FBI busted a criminal network that was using the Trojan horse Zeus to steal around $70 million from its victims.

Stuxnet – 2010

Stuxnet made headlines in 2010 as the first worm developed to target industrial control systems. The worm inflicted physical damage to Iranian nuclear facilities, particularly centrifuges. How? By exploiting vulnerabilities found in Windows to gain access to software used to control industrial equipment.

Stuxnet was also unique in that the worm was first introduced to computers using infected USB drives. Yes, physical USB sticks. Even today, Stuxnet is hailed as the world's first cyberweapon.

Poison Ivy – 2011

PoisonIvy does more than itch its victims. Known as a backdoor Trojan or remote access Trojan (RAT), PoisonIvy is used to gain access to a victim's computer. Although PoisonIvy is not a virus but a type of malware, it still deserves a spot on our list.

PoisonIvy was first identified in 2005. However, one of the most notable attacks using the Trojan occurred in 2011. Known as Nitro hacking attacks, PoisonIvy has been used to steal critical information to chemical manufacturers, government agencies and other organizations.

PoisonIvy is dangerous because threat actors can access computer for keylogging, screenshot etc. The Trojan is also used to steal passwords and other critical personal information.

WannaCry – 2017

The WannaCry ransomware attack took place in May 2017. The goal was simple: to hold a user's files hostage and get paid in Bitcoin.

The WannaCry attack used a hack known as EternalBlue to gain access to computers running Microsoft Windows. Once inside, WannaCry would encrypt computer data. Then users would see a message asking for Bitcoin payment for posting their files.

Unfortunately, WannaCry had its victims. In 2017, the damage was estimated at several billion. Even today, WannaCry still exists, emphasizing the importance of protecting against ransomware.

The computer virus is alive and well

As technology evolves, so does the work of cybercriminals. While you may see the years listed above and feel like viruses are a thing of the past, that couldn't be further from the truth.

Serious threats such as ransomware are alive and well. The best thing you can do? Protect yourself. Even the most basic security practices can help prevent viruses from infecting your devices.