Trojan Horse Examples (2023): The 6 Worst Attacks Ever

By Tibor Moes / Updated: May 2023

Trojan Horse Examples (2023): The 6 Worst Attacks Ever

Trojan Horse Examples

Imagine going to a yard sale and finding the perfect, handcrafted wooden horse. It’s charming and just the right size for your living room. You bring it home, only to discover it’s full of termites that slowly start to damage your home. That’s the digital equivalent of a Trojan Horse – a seemingly harmless piece of software that’s really a nasty bug.

In this article, we’ll explore the worst Trojan Horse attacks of all time, showing how they’ve wreaked havoc in the digital world.


A Trojan Horse is a piece of malware disguised as genuine software, that aims to infect your computer and alter your files and data. Some Trojan Horses may even give hackers access to your computer and personal information.

  1. ILOVEYOU (2000): This infamous Trojan began as an email attachment with the subject line “ILOVEYOU.” Upon opening, it sent itself to everyone in the user’s contact list and overwrote files on their computer.
  2. Zeus (2007): Primarily targeting Windows machines, Zeus stole banking information and credentials by logging key strokes and form entries.
  3. CryptoLocker (2013): This Trojan encrypted the user’s files and demanded a ransom to restore access.
  4. Emotet (2014): Originally a banking Trojan, Emotet evolved to distribute other malware and enable cybercriminals to install software on users’ computers.
  5. Dyre (2014): Also known as Dyreza, this Trojan targeted Windows users and stole banking and personal credentials.
  6. BlackEnergy (2015): Initially a simple tool for creating botnets, it evolved into a sophisticated Trojan used in various cyberattacks, including the infamous Ukraine power grid attack. 

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

Trojan Horse Examples In-Depth

1. The “ILOVEYOU” Attack (2000)

In the year 2000, a seemingly innocent email attachment named “LOVE-LETTER-FOR-YOU.txt.vbs” started circulating on the internet. Its welcoming title, “ILOVEYOU”, was enough to lure millions into opening it. However, behind this affectionate facade, there was a malicious piece of software known as a Trojan Horse.

This global digital attack took place in May and lasted for several days. The culprits behind this digital plague were two young Filipino programmers named Reonel Ramones and Onel de Guzman. Their creation didn’t discriminate between targets; it hit individuals, businesses, and even government institutions, showing that no one was safe from this type of cyber threat.

The “ILOVEYOU” virus quickly spread across the globe, hitting a staggering 50 million people in just ten days. In its wake, it caused an estimated $15 billion in damages and cleanup costs. This malicious software overwrote personal files and spread itself by emailing everyone in the victim’s address book.

Fortunately, the attack was eventually mitigated. Major email providers and internet security companies quickly updated their systems to filter out the offending email and attachment, and individuals were advised not to open any suspicious emails.

As for the perpetrators, although they were apprehended, they faced no legal consequences due to the absence of laws against writing malware in the Philippines at that time. However, this event did spur the creation of the country’s Electronic Commerce Act to penalize similar future activities.

2. The Zeus Attack (2007)

Seven years later, in 2007, a new Trojan Horse known as Zeus began its reign. Unlike the “ILOVEYOU” virus, Zeus was not just a one-time event. This Trojan was active for several years, continually evolving to bypass new security measures.

Believed to be the creation of a Russian hacker, Zeus primarily targeted Windows users and focused on stealing banking information. It was a more specialized threat than its predecessor, mainly affecting businesses in the financial sector. However, its geographic scope was no less impressive, affecting users worldwide.

The exact financial damage caused by Zeus is difficult to estimate due to its prolonged existence and the diverse nature of its attacks. However, one FBI report stated that a single Zeus botnet caused over $70 million in losses for various US businesses.

Zeus worked by logging keystrokes and form entries, enabling it to steal banking credentials and other sensitive personal data. The complexity of the Zeus Trojan made it challenging to counter. It took a concerted international effort, including law enforcement and cybersecurity firms, to finally shut down major Zeus operations in 2010.

Despite these efforts, the repercussions for the criminals behind Zeus were minimal. While some individuals associated with the use of Zeus were apprehended, the original author of the Trojan remains unknown. The Zeus source code was eventually leaked, leading to a surge of new Trojans based on its successful design. This lasting impact is a sobering reminder of the long-term effects of these types of cyber threats.

3. The CryptoLocker Attack (2013)

Fast forward to 2013, a digital menace named CryptoLocker made its first appearance. This Trojan Horse wasn’t content with just stealing data—it wanted to hold it hostage. CryptoLocker was a new breed of malware known as ransomware, and it was as sinister as it sounds.

Active between September 2013 and May 2014, CryptoLocker was the brainchild of an organized crime group believed to be based in Russia. This Trojan targeted individuals and businesses alike, but it had a particular fondness for small businesses, who often had less robust security measures in place.

CryptoLocker’s reach was global, but it hit hardest in the United States. The number of affected entities is unknown, but the financial impact was significant. It’s estimated that the Trojan caused a staggering $27 million in damages in just the first two months of its activity.

The Trojan worked by encrypting files on the victim’s computer and then demanding a ransom, usually in Bitcoin, to unlock them. This could include personal photos, business documents, or any other type of valuable data.

The countermeasures against CryptoLocker were a blend of prevention and cure. Antivirus companies updated their software to detect and block CryptoLocker, while law enforcement agencies and cybersecurity researchers worked to dismantle its infrastructure. In May 2014, Operation Tovar successfully took down the Gameover ZeuS botnet, which was used to distribute CryptoLocker, effectively stopping the ransomware.

Unfortunately, many victims paid the ransom before these measures were put in place, and the group behind the Trojan escaped without legal consequence. CryptoLocker marked a turning point in cybercrime, showing that data could be not just stolen, but held hostage, opening a new chapter in digital threats.

4. The Emotet Outbreak (2014)

Just a year later, in 2014, another Trojan called Emotet emerged. Initially designed as a banking Trojan like Zeus, Emotet evolved over time to become one of the most notorious Trojans to date.

The group behind Emotet, known as TA542 or Mummy Spider, is believed to have Eastern European roots. Their Trojan affected both individuals and various industries, with a particular emphasis on the banking sector.

Emotet had a global reach, but its activities were particularly concentrated in the United States and Western Europe. Although it’s challenging to estimate the exact number of people affected or the total financial damages, Emotet’s impact was significant enough to warrant a joint effort by multiple countries to take it down.

Emotet was versatile. It started as a banking Trojan, stealing financial data, but evolved into a delivery mechanism for other types of malware. This allowed it to adapt to various countermeasures and remain a significant threat for several years.

The fight against Emotet was a long one. Numerous updates to antivirus software and public awareness campaigns helped reduce its impact, but the real turning point came in 2021 when an international law enforcement operation dismantled its infrastructure. As a result, several individuals associated with Emotet were arrested, demonstrating that there can be legal consequences for these types of activities.

However, like the aftermath of the Zeus attack, the Emotet source code is still out there, a reminder that while specific threats can be neutralized, the danger of Trojan Horse attacks is ongoing.

5. The Dyre Invasion (2014)

In the same year that Emotet made its debut, another Trojan called Dyre, also known as Dyreza, burst onto the scene. Dyre continued the trend of Trojans targeting financial data, but it brought its unique methods to bear.

Dyre’s timeline of activity spanned from 2014 until late 2015. Its perpetrators, a group known as Evil Corp, were a well-organized cybercrime organization based in Russia. Dyre primarily targeted businesses, particularly those in the financial sector.

With a global reach, Dyre was particularly active in English-speaking countries, including the United States, the United Kingdom, and Australia. While it’s hard to pin down the exact number of businesses affected or the total financial damages, it’s known that Dyre was responsible for stealing millions of dollars.

Dyre’s method was to intercept traffic between the user’s browser and banking websites, capturing login credentials and other sensitive information. This man-in-the-middle attack allowed it to bypass encryption and two-factor authentication, making it a particularly nasty threat.

The end of Dyre came in November 2015, when a major part of its network was taken down, and several individuals associated with Evil Corp were arrested. However, the group remains active and continues to be a significant threat to cybersecurity.

6. The BlackEnergy Saga (2015)

BlackEnergy started its life in 2007 as a relatively simple tool for creating botnets, used primarily for DDoS attacks. However, it underwent a significant evolution in 2014, transforming into a sophisticated Trojan Horse used for cyber espionage and destructive attacks.

BlackEnergy’s major attacks, attributed to a group known as SandWorm, have targeted government institutions and critical infrastructure, particularly in Ukraine. While initially localized, the group’s activities have had international implications, including a significant power outage.

The most infamous BlackEnergy attack occurred in December 2015, when it was used to trigger a massive power outage in Ukraine. This marked the first known successful cyberattack on a power grid, highlighting the potential for cyber threats to cause real-world damage.

The nature of the data compromised by BlackEnergy varied depending on the target, but in many cases, it included sensitive government information and control systems for critical infrastructure.

Mitigating the threat of BlackEnergy has required a combination of patching vulnerable systems, improving security protocols, and international cooperation to track down the perpetrators. Although some individuals associated with the group have been identified, the threat of BlackEnergy and its successors remains ongoing.

BlackEnergy’s transformation and the scale of its attacks serve as a stark reminder of the potential for cyber threats to evolve and the real-world consequences they can have.

Conclusion – Staying Safe in the Digital World

As we’ve seen, the world of Trojan Horse attacks is a scary place, filled with clever disguises, nasty surprises, and real-world consequences. However, while the threat is real, it’s not insurmountable. With some simple steps and a little vigilance, we can all keep our digital homes safe from these hidden invaders.

One of the best defenses against Trojan Horses and other types of malware is keeping your devices up to date. Software updates often include patches for security vulnerabilities that these nasty bugs exploit. By regularly updating your devices, you’re not just getting the latest features—you’re also improving your security.

Another essential tool in your cybersecurity arsenal is reliable antivirus software for Windows like Norton, Bitdefender, McAfee, Panda, or Kaspersky. These programs can detect and block many types of malware, including Trojan Horses. They can also regularly scan your devices for any signs of an infection, helping to catch any threats that slip through the cracks.

However, it’s important to remember that no tool is perfect, and the best defense is a layered approach. Be cautious with emails and messages from unknown senders, avoid clicking on suspicious links, and never download attachments or software from untrusted sources.

Finally, education is a powerful weapon in the fight against cyber threats. The more you know about these threats and how they operate, the better prepared you’ll be to recognize and avoid them. Here are a few trusted resources where you can learn more:

  1. Stay Safe Online – A resource from the National Cyber Security Alliance with tips and information for individuals and businesses.
  2. The United States Computer Emergency Readiness Team (US-CERT) – Provides alerts and advice on current security threats and vulnerabilities.
  3. The European Union Agency for Cybersecurity (ENISA) – Offers a variety of resources, including reports, threat intelligence, and best practices for cybersecurity.
  4. The UK’s National Cyber Security Centre – Provides guidance and resources on cybersecurity for individuals, businesses, and public sector organizations.

Remember, in the digital world, just like in the real world, it’s always better to be safe than sorry. Stay vigilant, stay educated, and stay safe.

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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