Malware Examples (2023): The 14 Worst Attacks of All Time

By Tibor Moes / Updated: May 2023

Malware Examples (2023): The 14 Worst Attacks of All Time

Malware Examples

Imagine you’re at a bustling marketplace, wallet full, ready to shop. Suddenly, a crafty pickpocket snatches your wallet and splurges on their heart’s desire, leaving you empty-handed. In the digital world, such mischief-makers exist too, except they use malware – malicious software – to pick your virtual wallet.

This article will spotlight the 10 most common malware types and 14 most infamous malware attacks that have given countless people headaches.


Malware is software designed to cause harm to you or your devices. It includes many types, such as spyware, ransomware, trojan horses, and more. They can spread manually or automatically. And range from being an inconvenience, to incredibly destructive.

  1. ILOVEYOU (2000): Also known as “Love Bug,” this virus affected millions of computers worldwide, causing billions in damages.
  2. Code Red (2001): This worm affected computers running Microsoft’s IIS web server, causing a Distributed Denial of Service (DDoS) attack.
  3. Slammer/Sapphire (2003): Known for its rapid spread, this worm caused considerable disruption to internet services.
  4. Mydoom (2004): Often cited as one of the fastest-spreading email-based worms, Mydoom caused significant disruption and financial damage.
  5. Conficker (2008): A worm that targeted Windows OS, Conficker created a botnet, which was potentially capable of destructive actions but was mostly used for distributing spam and additional malware.
  6. Stuxnet (2010): This was a sophisticated piece of malware allegedly created by the U.S. and Israeli governments to disrupt Iran’s nuclear program.
  7. CryptoLocker (2013): This was one of the first widespread ransomware attacks, encrypting users’ files and demanding a ransom for their release.
  8. Heartbleed (2014): This wasn’t a malware but a critical vulnerability in the OpenSSL cryptographic software library, which allowed attackers to steal protected information.
  9. WannaCry (2017): A massive ransomware attack that impacted businesses and organizations (including the NHS in the UK) across the globe.
  10. NotPetya (2017): Initially appearing as ransomware, NotPetya was designed more to disrupt systems rather than to make money. It caused significant damage, particularly in Ukraine.
  11. Bad Rabbit Ransomware (2017): A ransomware targeting media organizations in Russia and Eastern Europe, posing as a s an Adobe Flash update, and causing disruptions and financial loss.
  12. VPNFilter (2018): Malware targeting routers and storage devices, infected over 500,000 devices worldwide. It had the ability to steal information, exploit devices, and even render them unusable.
  13. Emotet (2018-2019): Evolved from a banking Trojan to a versatile malware distributor, that offered malware-as-a-service to other cybercriminals. causing global data and system damage.
  14. Ryuk Ransomware (2018-2020): Ransomware infiltrating networks in conjunction with other malware to infiltrate networks, move laterally, and then encrypt critical data and systems.

Don’t become a victim of malware. Protect your data and devices with the best antivirus software and your privacy with the best VPN service.

Malware Examples – In-depth

1. ILOVEYOU (2000) – A Love Bug That Brought Heartache

In May 2000, millions of computer users worldwide found an email in their inbox with a subject line that warmed their hearts: “I LOVE YOU”. However, this seemingly affectionate message was the vehicle for one of the most damaging viruses in history, aptly named “ILOVEYOU” or “Love Bug”.

While it’s still unclear who unleashed the Love Bug, the trail led to two young programmers in the Philippines. Unfortunately, at the time, the Philippines had no laws against writing malware, so no legal consequences came their way.

The Love Bug was not choosy about its victims. It targeted both individuals and businesses, using the address books of infected computers to replicate and spread, turning the virus into a global problem almost overnight.

The financial damage was staggering, with estimates ranging up to $10 billion. This was due to the widespread disruption it caused, affecting systems in government and private sector organizations, including the Pentagon, the CIA, and the British Parliament.

The Love Bug virus had a voracious appetite for data. It overwrote files, replacing them with copies of itself, which led to massive data loss.

Countermeasures were rapidly deployed once the scale of the attack became evident. Companies and organizations worldwide updated their antivirus software to detect the virus, and internet service providers tried to filter out the malicious emails.

Despite the rapid response, the Love Bug served as a wake-up call to the world about the potential devastation of malware attacks.

2. Code Red (2001) – A Worm That Crawled Across the Globe

Fast forward a year to July 2001 when a new cyber-threat emerged. Named “Code Red”, this malicious worm was so potent that it brought down some of the internet’s most robust infrastructure, including the White House’s web servers.

The perpetrators of Code Red remain unknown. However, their clever programming allowed the worm to exploit a vulnerability in Microsoft’s IIS web server, enabling it to self-replicate and spread.

Code Red was an equal opportunity offender, infecting both businesses and home users alike. Its reach was international, with hundreds of thousands of systems affected worldwide.

The financial damage caused by Code Red is estimated at $2 billion, predominantly due to system downtime and the costs of implementing protective measures.

The Code Red worm was an indiscriminate disruptor, defacing websites and causing systems to crash, but it didn’t specifically target personal or financial data.

Once Microsoft identified the vulnerability, they swiftly released a patch to fix it. The worm’s spread was eventually halted by a coordinated response from cybersecurity professionals who advised users to install the patch and update their antivirus software.

The Code Red saga reiterated the importance of regularly updating software and maintaining robust cybersecurity measures to prevent such infections. Despite the lack of legal action due to the anonymous nature of the attack, Code Red remains a potent reminder of the far-reaching effects of malware.

3. Slammer/Sapphire (2003) – The Speedy Saboteur

January 2003 saw the dawn of a new kind of digital threat — one that valued speed above all else. This worm, known as Slammer (or Sapphire), raced through the internet, doubling its number of victims approximately every 8.5 seconds, rendering it one of the fastest-spreading pieces of malware ever seen.

The source of the Slammer attack remains a mystery. The worm targeted a vulnerability in Microsoft SQL Server, affecting businesses predominantly, but also impacting individuals who had the vulnerable software installed.

Slammer didn’t discriminate geographically. It quickly spread worldwide, causing global internet slowdowns and knocking out entire networks. The South Korean internet, for instance, was down for approximately 12 hours.

In terms of financial damage, estimates suggest that Slammer caused over $1 billion in losses. These costs were primarily due to the disruptions to services, including airline reservation systems and ATM networks.

The Slammer worm didn’t target specific data; instead, it aimed to cause disruption. By generating massive network traffic, it overwhelmed systems and rendered them unusable.

The rapid response from software and network security professionals eventually stemmed the worm’s spread. Microsoft released a patch to fix the vulnerability, and ISPs implemented measures to block the traffic generated by the worm.

While no legal consequences ensued due to the anonymity of the attacker, the Slammer incident underscored the importance of regular software updates and robust security practices.

4. Mydoom (2004) – The Email Epidemic

January 2004 brought the advent of Mydoom, an infamous worm that still holds the record for being one of the fastest-spreading email-based worms in history.

Although the identity of the perpetrator remains unknown, some speculated that Mydoom originated from Russia. This malicious software was primarily spread via email but also through peer-to-peer networks.

Mydoom targeted both individuals and businesses, with a seemingly innocuous email that tricked people into clicking on a malicious attachment. Once activated, the worm then forwarded itself to all the contacts in the victim’s address book.

The reach of Mydoom was global, affecting millions of computers around the world. The financial damage caused by Mydoom was monumental, estimated at $38 billion. This cost was primarily due to productivity loss and the expenses related to updating antivirus software to detect and remove the worm.

The worm didn’t compromise specific types of data but used the infected computers to launch Distributed Denial of Service (DDoS) attacks, which caused widespread disruption.

Countermeasures involved updating antivirus software to detect Mydoom and educating users not to open suspicious emails. Over time, the worm’s effects waned, but it took a considerable time to fully eradicate it from all systems.

Despite the magnitude of the Mydoom attack, no legal consequences were ever imposed due to the anonymity of the attackers. However, the event served as a stark reminder of the potential dangers of clicking on unknown email attachments.

5. Conficker (2008) – The Master of Disguise

In November 2008, a new type of worm began to make its presence known. Named Conficker, it was a worm that showcased an unprecedented ability to resist countermeasures, making it one of the most resilient pieces of malware to date.

The creators of Conficker have never been definitively identified, but their handiwork predominantly targeted Windows-operated computers, affecting both individuals and businesses worldwide.

Conficker’s geographic reach was staggering, with over 9 million computers infected globally at its peak. The financial impact caused by the worm is difficult to calculate, but estimates put it in the billions of dollars, mainly due to the costs of detection, mitigation, and repair.

Conficker didn’t compromise specific data. Instead, it created a network of infected computers (a botnet), which could potentially be used to launch other cyber-attacks.

Countermeasures against Conficker were challenging due to its ability to resist removal and its constant evolution. Microsoft released a patch, and cybersecurity professionals worked tirelessly to remove the worm from infected systems.

Despite the lack of legal consequences for the creators of Conficker, the event highlighted the need for improved security practices, including the importance of regular software updates.

6. Stuxnet (2010) – The Silent Saboteur

In 2010, a new breed of malware entered the scene, raising the stakes in the realm of cyber warfare. This malicious software, known as Stuxnet, was no ordinary piece of malware — it was a cyberweapon.

Stuxnet’s creators were state-sponsored entities, believed to be the U.S. and Israeli governments, with a very specific target — Iran’s nuclear program.

The geographic scope of the Stuxnet attack was limited primarily to Iran, where it caused substantial disruption to the country’s nuclear facilities. However, the worm did find its way into other systems worldwide, albeit with minimal impact.

The financial damage caused by Stuxnet is hard to quantify since its primary goal was to disrupt Iran’s nuclear enrichment processes rather than to inflict financial harm.

Stuxnet didn’t compromise personal or financial data. Instead, it caused physical damage by making changes to the speed of the centrifuges in the nuclear facilities, causing them to tear themselves apart.

The countermeasures against Stuxnet involved a mix of digital forensics and industrial system repairs. The worm was eventually neutralized, but not before it had achieved its objective.

In terms of legal consequences, none were implemented as the alleged perpetrators were state actors. The Stuxnet event served as a grim reminder of the potential for malware to cause physical damage and disrupt critical infrastructure.

7. CryptoLocker (2013) – The Digital Kidnapper

In September 2013, the digital world was introduced to a new kind of threat — ransomware. CryptoLocker, the harbinger of this new age of cybercrime, used an all too familiar method for spreading: malicious emails.

The criminal group behind CryptoLocker, believed to be based in Russia, targeted individuals and businesses alike. Once a user clicked on a seemingly harmless email attachment, CryptoLocker would spring into action, encrypting the user’s files and demanding a ransom for their release.

The CryptoLocker attack was global in scale, affecting hundreds of thousands of computers worldwide. The financial damage caused by the ransomware was significant, with estimates exceeding $30 million, not including the costs of data recovery and system repairs.

Unlike previous malware examples, CryptoLocker was explicitly designed to compromise personal data. It held users’ files hostage, encrypting photos, documents, and other personal data until the ransom was paid.

Countermeasures to stop CryptoLocker included updating antivirus software to detect the ransomware and advising users not to pay the ransom. Additionally, a global law enforcement operation managed to seize a portion of the botnet infrastructure that CryptoLocker used to operate, significantly reducing its impact.

In terms of legal consequences, several individuals associated with the CryptoLocker operation were arrested. The event highlighted the growing threat of ransomware and the need for robust data backups and careful email practices.

8. Heartbleed (2014) – The Silent Listener

April 2014 brought a new kind of digital threat, not a piece of malware, but a vulnerability in the very software that was supposed to keep our data safe. This weakness, known as Heartbleed, affected the OpenSSL cryptographic software library, which is widely used to secure communications on the internet.

Heartbleed was not the creation of a malicious actor, but a flaw inadvertently introduced by one of the OpenSSL contributors. This flaw could be exploited by anyone aware of its existence, allowing them to steal supposedly protected information.

Heartbleed had a global impact, as OpenSSL is used worldwide by web servers, email services, instant messaging, and virtual private networks. It’s challenging to estimate the financial damage caused by Heartbleed, but the costs associated with patching systems and updating security certificates were considerable.

Unlike traditional malware, Heartbleed allowed attackers to access sensitive data such as usernames, passwords, and encryption keys directly from the memory of the affected systems, posing a significant risk to personal and financial information.

Countermeasures against Heartbleed involved patching the OpenSSL vulnerability and replacing the security certificates for the affected services. Users were also advised to change their passwords after the affected services had been secured.

As Heartbleed was not an intentional attack, there were no legal consequences. However, the event served as a stark reminder of the importance of rigorous software testing and the potential risks associated with relying on open-source software.

9. WannaCry (2017) – The Digital Pandemic

In May 2017, a new type of ransomware began to spread across the globe, locking out users from their data and demanding a ransom in Bitcoin. This ransomware, known as WannaCry, quickly became infamous due to its wide reach and damaging impact.

The culprits behind WannaCry are believed to be a hacker group known as Lazarus, which has ties to North Korea. Their target was primarily businesses, but individuals were also affected.

WannaCry spread to over 150 countries, affecting an estimated 200,000 computers. The financial damage caused by WannaCry is difficult to calculate but is estimated to be in the billions of dollars, factoring in the ransom payments, system repairs, data recovery, and associated downtime.

WannaCry encrypted users’ files, making them inaccessible and effectively compromising all types of personal and professional data.

Countermeasures against WannaCry included a fortuitous kill switch discovered by a cybersecurity researcher, along with patches released by Microsoft to close the exploited vulnerability. Users were also advised not to pay the ransom, as there was no guarantee of data recovery.

While some individuals linked to the Lazarus group were sanctioned, no specific legal action related to the WannaCry attack has been reported. The attack served as a stark reminder of the importance of regular software updates and robust data backup practices.

10. NotPetya (2017) – The Destructive Imposter

Just a month after the WannaCry attack, in June 2017, a new cyber threat emerged. Initially thought to be a variant of the Petya ransomware, this destructive malware was dubbed NotPetya due to its distinct features.

Attributed to the Russian military, NotPetya was primarily aimed at Ukrainian businesses and infrastructure as part of the ongoing conflict between the two nations. However, it quickly spread to other countries, affecting businesses worldwide.

The financial damage caused by NotPetya is estimated to exceed $10 billion, making it one of the costliest cyberattacks in history. Companies like Maersk and FedEx reported losses in the hundreds of millions due to the disruption.

Unlike traditional ransomware, NotPetya was not designed for financial gain but rather for maximum disruption. It encrypted the master file table, rendering the entire system unusable.

Countermeasures against NotPetya involved patching the exploited vulnerability and recovering systems from backups. However, the damage caused was extensive and took a significant amount of time to repair.

In terms of legal consequences, the U.S. and UK governments publicly attributed the attack to the Russian military. However, no specific legal actions were reported. The event served as a reminder of the potential for cyber warfare to cause significant collateral damage.

11. Bad Rabbit (2017) – The Hopping Nightmare

In October 2017, a new cyber menace emerged from the digital shadows. Dubbed “Bad Rabbit,” this ransomware attack hopped from one system to another, spreading chaos in its wake.

The instigators of Bad Rabbit remain unknown, but cyber sleuths believe they have links to the creators of the NotPetya ransomware, suggesting they could be state-sponsored actors. Their targets were primarily media organizations in Russia and Eastern Europe.

The financial impact of Bad Rabbit was substantial, though it didn’t reach the dizzying heights of its ransomware kin like WannaCry or NotPetya. It caused significant service disruptions, with the financial fallout estimated in the millions of dollars.

Bad Rabbit, true to its ransomware nature, encrypted a wide range of file types, locking users out of their documents, images, and other valuable data. It then demanded a Bitcoin ransom for the decryption key.

Countermeasures against Bad Rabbit involved updating security software to detect and block the ransomware, and providing users with advice on how to avoid falling for the fake Adobe Flash update that spread the infection.

Unfortunately, there have been no reported legal consequences for the authors of Bad Rabbit. However, the attack served as another stark reminder of the constant evolution of cyber threats and the importance of staying vigilant against suspicious downloads and updates.

12. VPNFilter (2018) – The Hidden Saboteur

In 2018, cybersecurity researchers uncovered a new threat lurking in the devices that keep us connected to the internet. Named “VPNFilter,” this malware targeted routers and network-attached storage devices, stealthily carving out a stronghold in our homes and offices.

Attributed to the Fancy Bear hacking group with ties to the Russian military, VPNFilter demonstrated a sophisticated level of design and execution. It infected over 500,000 devices worldwide, with no preference for individuals, businesses, or governments — anyone with a vulnerable device was a potential victim.

The financial damage caused by VPNFilter is hard to quantify, as it primarily aimed to create a network of compromised devices for potential use in future attacks. However, the cost of identifying, mitigating, and removing the infection from half a million devices would have been substantial.

VPNFilter was capable of stealing sensitive data passing through the infected devices, but its most disturbing feature was its ability to render the devices completely unusable — a feature that could have been used to cause widespread internet outages.

Countermeasures against VPNFilter involved a multi-pronged approach. The FBI seized a domain that was a critical part of the malware’s command-and-control infrastructure, disrupting its operation. Meanwhile, device owners were advised to reboot their devices and update their firmware to remove the infection.

While no specific legal consequences were reported for the VPNFilter attack, the incident underscored the global nature of cyber threats and the potential for seemingly innocuous devices to be turned into weapons in the digital age.

13. Emotet (2018-2019) – The Malware Chameleon

Emotet, first detected in 2014, was a shape-shifting threat that started as a banking Trojan but evolved into a malware distribution service. It had its heyday in 2018 and 2019, and its creators, believed to be an organized crime group from Eastern Europe, didn’t discriminate in their targets, aiming at individuals, businesses, and governments alike.

Emotet was an international nuisance, infecting hundreds of thousands of computers worldwide. Its financial impact was substantial, resulting in millions of dollars in damages from data theft and system disruption.

Emotet’s primary method of compromise was through phishing emails. It would infect a computer and then steal email contacts and send itself to them, often using convincing fake emails. The stolen data could include anything on the infected system, from personal files to financial information.

Countermeasures against Emotet included a concerted international law enforcement effort that disrupted its infrastructure in 2021. Users were also advised to keep their software updated and to be cautious of suspicious emails.

While law enforcement actions did disrupt Emotet’s activities, it’s unclear if any specific legal actions were taken against its operators. However, the story of Emotet serves as a stark reminder that even a known threat can evolve into something far more dangerous.

14. Ryuk Ransomware (2018-2020) – The Ruthless Extortionist

First appearing in 2018, Ryuk ransomware quickly made a name for itself. Believed to be the work of an Eastern European crime group, Ryuk targeted businesses and institutions worldwide, often those that couldn’t afford downtime, like hospitals.

Ryuk’s financial toll has been significant. It’s estimated to have extorted over $61 million in ransom payments by the end of 2019. However, this figure doesn’t account for the costs of disruption, data loss, and system recovery.

Unlike many other forms of malware, Ryuk didn’t spread itself. Instead, its operators used other malware like Emotet and TrickBot to gain access to a network, move laterally within it, and then deploy Ryuk to encrypt critical files.

Countermeasures against Ryuk have included removing the initial infection vectors like Emotet and TrickBot, improving network security to prevent lateral movement, and maintaining offline backups to recover encrypted files.

While there have been no reported arrests directly linked to Ryuk, the FBI and other law enforcement agencies have issued alerts about it and provided guidance on preventing such attacks. The Ryuk saga is a sobering reminder of the potential consequences of ransomware attacks and the importance of robust cybersecurity measures.

Malware Types

Here are the 10 most common malware types. Below it are real-life malware examples that have haunted the web since its beginning.

  1. Adware: Ever been bombarded with pop-ups while browsing? That’s adware. It’s unwanted software designed to throw ads onto your screen, often within your web browser.
  2. Botnets: Imagine your computer becomes a zombie, part of an army of infected devices without your knowledge. That’s a botnet, a network of private computers infected and controlled as a group.
  3. Keyloggers: Picture every keystroke you make being recorded — passwords, messages, everything. That’s a keylogger, a stealthy tool that tracks your keyboard activity.
  4. Phishing: You receive an email that looks legitimate, asking for personal info. You trust it, you respond. Unfortunately, you’ve just been phished. Phishing is a deceptive method of gathering your personal information.
  5. Ransomware: One day, your files are suddenly encrypted. To unlock them, you must pay a ransom. That’s ransomware, a type of malware holding your data hostage.
  6. Rootkits: Imagine a thief sneaking into your house and living undetected in the basement. A rootkit does the same with your device, enabling unauthorized users to control your system without being detected.
  7. Spyware: Think about someone spying on every move you make on your device. That’s spyware, software that covertly transmits your activities from your hard drive.
  8. Trojans: You download a seemingly safe software, but it secretly opens the backdoor for hackers. That’s a Trojan, malware disguised as legitimate software, granting unauthorized access to your system.
  9. Viruses: Like a biological virus, a computer virus self-replicates and spreads, infecting your programs and messing with your device’s health.
  10. Worms: Imagine a worm eating through an apple. In the digital world, a worm replicates itself to spread to other computers, munching through networks and potentially causing havoc.

Conclusion – Staying Safe in the Digital Landscape

As we journey through the digital landscape, it’s clear that malware is a persistent threat, capable of evolving and adapting to our defenses. But while the tales of these infamous attacks might seem intimidating, remember that we’re not defenseless.

Updating your devices is one of the most straightforward steps you can take. Software updates often include patches for security vulnerabilities, so keeping your software up-to-date can help shield you from many threats.

Investing in one of the best antivirus software for Windows 11 like Norton, Bitdefender, McAfee, Panda or Kaspersky is also a wise move. These digital sentinels work tirelessly to detect and neutralize threats before they can cause harm. They’re continually updated to respond to the latest threats, providing an ever-evolving line of defense.

Beyond these steps, being aware of the threats and understanding how they operate can provide valuable protection. Be cautious of unsolicited emails, especially those with attachments or links. Be wary of too-good-to-be-true offers and requests for sensitive information.

The world of cybersecurity might seem like a daunting place, but there are plenty of resources available to help you navigate it safely. Here are a few trusted sources where you can learn more:

Stay safe, stay updated, and remember — the best defense is being informed and prepared.

Author: Tibor Moes

Author: Tibor Moes

Founder & Chief Editor at SoftwareLab

Tibor is a Dutch engineer and entrepreneur. He has tested security software since 2014.

Over the years, he has tested most of the best antivirus software for Windows, Mac, Android, and iOS, as well as many VPN providers.

He uses Norton to protect his devices, CyberGhost for his privacy, and Dashlane for his passwords.

This website is hosted on a Digital Ocean server via Cloudways and is built with DIVI on WordPress.

You can find him on LinkedIn or contact him here.

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