What is a Trojan Horse? Everything You Need to Know (2023)

By Tibor Moes / Updated: June 2023

What is a Trojan Horse? Everything You Need to Know (2023)<br />

What is a Trojan Horse?

Did you know that one of the most widespread and dangerous types of cyber threats is hiding in plain sight? It’s called a Trojan horse, and it’s disguised as a seemingly harmless file or program.

In this blog post, we’ll explore Trojan horses, from understanding how they operate, to how to protect yourself from these stealthy invaders.


  • A Trojan Horse is a type of malware that appears harmless or useful, tricking users into installing it onto their systems.

  • Once installed, it can steal data, spy on user activity, or gain backdoor access to systems, often without detection.

  • Prevention involves careful downloads, updated antivirus software, and ongoing user education about suspicious digital behavior.

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

Defining the Trojan Horse

A Trojan horse, or simply a Trojan, is a type of malware that masquerades as legitimate software, only to cause harm to your data or network once it’s activated. The name “Trojan” comes from the infamous story of the hollow wooden horse used by the Greeks to infiltrate the city of Troy during the Trojan War.

Trojans can be found in various forms, such as suspicious codec packs or cracked programs, and they’re usually delivered through emails or downloaded files. Unlike viruses, which self-replicate and spread on their own, Trojans require user interaction to infiltrate a system.

Once inside, they have the potential to steal sensitive data, disrupt your network, or even completely destroy your computer.

How Trojans Operate

Trojans typically disguise themselves as legitimate files or programs and rely on the user to download and open them. Once activated, they can cause a wide range of damage by loading other malware, executing malicious code, setting up botnets, stealing data, and monitoring web traffic.

Botnets, for instance, are networks of infected computers, or “zombie computers,” that are covertly controlled by cybercriminals. These botnets can be used to launch distributed denial-of-service (DDoS) attacks, which can render websites and networks completely inaccessible.

As you can see, Trojans are not something to be taken lightly, and it’s crucial to take preventive measures to protect yourself from these cyber threats.

Common Varieties of Trojan Malware

There are several types of Trojan malware that can be encountered, each with its own unique set of tactics and objectives. Some of the most common types include backdoor Trojans, ransomware Trojans, and banking Trojans.

Let’s take a closer look at each of these varieties and how they operate.

Backdoor Trojans

Backdoor Trojans are particularly insidious because they can give hackers remote access to your computer, allowing them to control it from afar. Once they have this access, they can load additional malware onto your system, make it vulnerable to attack, and even set up botnets without your knowledge.

These Trojans can also be remotely updated by their creators, making it difficult for antivirus software to detect them with new definitions. Furthermore, they can add new functions to their arsenal, increasing the potential harm they can cause.

One example of this is the difference between a downloader Trojan and a dropper Trojan: a downloader Trojan requires access to a network resource to fetch malware, while a dropper Trojan already has the malicious components within the program package.

Ransomware Trojans

Ransomware Trojans are a particularly nasty breed of malware that encrypts files on your computer and demands a ransom payment in order for you to regain access to them. They often infiltrate systems through malicious links or attachments in emails, or by exploiting software vulnerabilities. Once your files are encrypted, the attackers typically demand payment in cryptocurrency to provide the decryption key.

To protect yourself from ransomware Trojans, it’s essential to exercise caution when navigating the internet and managing your files. This includes being wary of clicking on suspicious links and attachments, keeping your software up to date, and using cybersecurity software to monitor and safeguard your system.

Banking Trojans

Banking Trojans are designed to steal sensitive financial information from their victims, often leading to monetary theft and fraud. They employ a variety of tactics to target online banking, such as downloading and sending files remotely, snatching data from a clipboard, executing executable files, grabbing cookies and passwords, or rerouting website traffic to malicious ones.

To protect yourself from banking Trojans, it’s essential to practice online safety measures, including using strong passwords, avoiding suspicious links, and employing cybersecurity software to monitor and safeguard your system. Additionally, keeping your system updated will help patch any security vulnerabilities that could be exploited by attackers.

Recognizing a Trojan Infection

Detecting a Trojan infection can be challenging, as these malicious programs often work behind the scenes. However, there are some telltale signs to look out for, including unusual computer activity, sudden changes in your computer settings, and a drop in performance.

If you suspect a Trojan infection, it’s essential to act swiftly to minimize the damage. Specialized software tools like Trojan scanners and malware-removal programs can help identify and eliminate these threats.

Keep in mind that adware and potentially unwanted programs (PUPs) can sometimes be mistaken for Trojan horses due to their similar delivery methods, but unlike Trojans, adware and PUPs don’t try to stay hidden once installed.

Real-World Trojan Attacks

Trojan attacks are not just theoretical; they have caused significant harm in the real world. Some notable examples of Trojan attacks include the Emotet botnet, the Zeus banking Trojan, and the NotPetya ransomware attack.

The Emotet botnet is a malware distribution platform that has been used to spread other malicious software like banking Trojans and ransomware. The Zeus banking Trojan, on the other hand, specifically targets financial information, stealing banking credentials and other sensitive data from infected computers.

Finally, the NotPetya ransomware attack encrypted files on victims’ computers and demanded ransom payments for their release. These examples serve as a reminder of the very real threat posed by Trojan malware.

Mobile Device Trojans

Trojans are not limited to computers; they can also target mobile devices such as smartphones and tablets. Mobile device Trojans often disguise themselves as legitimate apps, typically from unofficial sources, with the goal of stealing data and generating revenue for their creators.

One example of a mobile device Trojan is the Switcher Trojan, which targets Android devices. It infects users’ devices and attacks the routers of their wireless networks, allowing cybercriminals to redirect traffic on Wi-Fi-connected devices for malicious purposes.

To protect yourself from mobile device Trojans, it’s essential to download apps only from trusted sources, such as official app stores, and to stay vigilant when managing your device’s security settings.

Preventing and Protecting Against Trojan Horses

The best defense against Trojan horses is a combination of responsible online behavior, investment in cybersecurity software, and keeping your system up to date.

In the following sections, we’ll delve deeper into these preventive measures and how they can help secure your system from the ever-present threat of Trojan malware.

Online Safety Practices

Practicing responsible online behavior is essential in preventing and protecting against Trojan horses. This includes using strong and unique passwords for your accounts, not sharing your passwords with others, protecting your router with a strong password and updated firmware, and staying informed about common online scams.

Additionally, it’s crucial to be cautious when clicking on links or downloading files from unknown sources, as Trojans often disguise themselves as legitimate files or programs and rely on user interaction to infiltrate a system.

By following these online safety practices, you can significantly reduce your risk of falling victim to a Trojan attack.

Cybersecurity Software

Investing in cybersecurity software is another critical component of protecting yourself against Trojan malware. This includes using antivirus software, firewalls, intrusion detection and prevention systems, and other security tools tailored to your specific needs, such as network security, cloud security, endpoint security, mobile security, IoT security, and application security.

Cybersecurity software can help detect and prevent threats from infiltrating your device, keeping your system safe from Trojan attacks and other forms of malware. Make sure to choose reliable and reputable cybersecurity software to ensure the best protection possible.

System Updates

Keeping your system updated is an often overlooked but essential aspect of preventing and protecting against Trojan horses. System updates often include security patches that address vulnerabilities in your operating system and software, which could be exploited by attackers to gain access to your system.

Regularly updating your system not only helps to patch security vulnerabilities, but also ensures that your device runs smoothly and efficiently, providing new features and improving overall performance. By staying up to date with system updates, you can bolster your defenses against Trojan malware and other cyber threats.

Responding to a Trojan Infection

If you suspect a Trojan infection on your device, it’s essential to act quickly to minimize the damage. First, contact a reliable cybersecurity professional who can help you identify and remove the infection, as well as implement safeguards to prevent future attacks.

Next, use an antivirus program and malware removal service to scan your device and eliminate any malicious files. Be sure to identify the infected files, disable the System Restore function, restart your computer in safe mode, access the Add or Remove programs in the control panel, and remove and delete the infected programs.

Finally, delete all program files associated with the Trojan application. Following these steps will help ensure the successful removal of the Trojan infection and restore your device’s security.


In this blog post, we’ve explored the world of Trojan malware, shedding light on how they operate, the various types, and the real-world implications of these cyber threats. We’ve also discussed the importance of practicing responsible online behavior, investing in cybersecurity software, and keeping your system updated to prevent and protect against Trojan horses. By following the tips and strategies outlined here, you can significantly reduce your risk of falling victim to a Trojan attack and keep your valuable data and devices safe from harm. Stay vigilant, stay informed, and stay secure.

How to stay safe online:

  • Practice Strong Password Hygiene: Use a unique and complex password for each account. A password manager can help generate and store them. In addition, enable two-factor authentication (2FA) whenever available.
  • Invest in Your Safety: Buying the best antivirus for Windows 11 is key for your online security. A high-quality antivirus like Norton, McAfee, or Bitdefender will safeguard your PC from various online threats, including malware, ransomware, and spyware.
  • Be Wary of Phishing Attempts: Be cautious when receiving suspicious communications that ask for personal information. Legitimate businesses will never ask for sensitive details via email or text. Before clicking on any links, ensure the sender's authenticity.
  • Stay Informed. We cover a wide range of cybersecurity topics on our blog. And there are several credible sources offering threat reports and recommendations, such as NIST, CISA, FBI, ENISA, Symantec, Verizon, Cisco, Crowdstrike, and many more.

Happy surfing!

Frequently Asked Questions

Below are the most frequently asked questions.

What is a Trojan horse in simple words?

A Trojan Horse is a malicious computer program disguised as something harmless. It’s typically downloaded unknowingly by the user and can cause damage to a computer system once it’s been activated.

It’s important to take precautions against Trojans, as they can be used for a variety of malicious activities.

Is a Trojan horse good or bad?

No, a Trojan horse is not good. It is a type of malware that is designed to damage your computer and steal data from you. It can often go undetected by traditional antivirus software, so it is important to be aware of the signs of a Trojan horse attack in order to protect yourself and your data.

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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