You log onto your computer and notice that something’s not right. Among the many unsettling things, your computer is suddenly crashing or freezing for no apparent reason, odd pop-up ads are appearing on your screen, and new applications have been added that you do not remember installing. If you’ve found yourself in this situation, there’s a real possibility you could have a Trojan virus on your computer.

Trojan viruses can not only steal your most personal information, but also put you at risk for identity theft and other serious cybercrimes. In this post, we’ll examine what Trojan viruses are, where they come from, how to remove the virus, and maintain peace of mind online.

What is a Trojan virus?

A Trojan virus, sometimes called a Trojan horse virus, is a type of malicious software that tricks you into installing it, disguised as a real, operational program. Named after the ancient Greek story of the Trojan Horse, where soldiers hid inside a giant wooden horse to infiltrate the city of Troy, a Trojan virus hides malicious code within a seemingly legitimate program, such as a free game, a software utility, or even a document. When you run the program, you unknowingly unleash the malware onto your system, allowing it to perform harmful actions in the background.

Is a Trojan a virus or malware?

A Trojan is a type of malware, but it is not technically a virus. The term malware is a broad category that includes all types of malicious software, such as viruses, worms, spyware, ransomware, and Trojans. The key difference lies in how they spread. A traditional computer virus is defined by its ability to self-replicate; it infects other clean files and spreads itself without user intervention. A Trojan horse virus, on the other hand, cannot replicate on its own. It relies on tricking you, the user, into downloading and executing it. While both are malicious, a virus spreads itself, whereas a Trojan needs to be delivered.

Key differences between Trojans and other viruses

The primary difference between a Trojan and other malware, such as viruses and worms, is its method of operation. 

  • Replication: A Trojan does not self-replicate, while viruses attach to and infect other files, and worms are standalone programs that spread across networks. 
  • Infection method: A Trojan’s success depends on social engineering—convincing a user to run it. In contrast, viruses spread when an infected file is executed, and worms actively exploit vulnerabilities to propagate automatically. 
  • Payload delivery: A Trojan’s sole purpose is to act as a delivery vehicle for its malicious payload, whether that’s a keylogger, spyware, or a backdoor. While viruses also carry payloads, their primary design includes replication, which a Trojan lacks.

Common motives behind Trojan attacks

Cybercriminals use Trojans as versatile tools for a wide range of malicious objectives. The most common motive is financial gain, where Trojans like the infamous Zeus malware are used to steal banking credentials, credit card numbers, and cryptocurrency wallet keys.

When espionage is the key objective, state-sponsored or corporate attackers deploy Trojans to steal sensitive government secrets or valuable intellectual property. Some attackers are driven by hacktivism, using Trojans to deface websites or disrupt services to make a political statement.

Trojans are also critical for botnet recruitment. They infect countless devices and force them to join a network controlled by the hacker, which can then be used to launch massive distributed denial of service (DDoS) attacks. Increasingly, Trojans serve as the delivery mechanism for ransomware, encrypting all your files and demanding payment. 

Finally, simple credential harvesting remains a core use. Trojans quietly collect login details of all your online accounts, which are then sold on the dark web or used for identity theft.

Long-term consequences of Trojan attacks

The impact of a Trojan virus can be severe, extending far beyond simple computer problems. These malicious programs are primary tools for cybercriminals engaged in data theft and credential harvesting, stealing everything from personal photos to login details for your sensitive accounts. This can lead to direct financial loss through unauthorized bank transfers or fraudulent purchases. Some Trojans deploy ransomware, locking you out of your own files and demanding payment. 

Ultimately, this can all culminate in full-blown identity theft, where criminals use your stolen information to commit fraud such as opening credit cards and taking out loans, or even committing crimes in your name, which can take years and significant effort to resolve and recover from.

For businesses, the impact can include catastrophic data breaches, loss of customer trust, and severe reputational damage. This is why preventing an infection is so crucial. 

Common signs you may be infected

Aside from your computer slowing down, crashing, or freezing; being bombarded with pop-up ads or security alerts; or showing unfamiliar applications you did not install, other symptoms of a Trojan virus include:

  • Your antivirus software or firewall being disabled without your knowledge
  • A changed web browser or being redirected to unwanted websites
  • Unusual network traffic even when your computer is idle
  • Files are disappearing, becoming encrypted, or being moved to another location.
  • Unusual system behavior, like random shutdowns, restarts, or errors
  • Being locked out of your computer

How Trojans work behind the scenes

Once a Trojan virus is executed, it works like a secret agent infiltrating your device. Its first action is to deliver its malicious payload, which could be anything from spyware that records your keystrokes to ransomware that encrypts your files. To operate freely, the Trojan will attempt to trick the operating system into granting it administrator-level control, similar to a burglar getting a master key to every room in your house.

After gaining control, the Trojan establishes persistence and permanence, modifying system files to ensure it launches automatically every time you start your device. Next, it will connect to a remote server operated by the attacker, who will send new commands, update the malware, or steal your personal files, financial information, and passwords. 

To avoid being caught, advanced Trojans use stealth techniques like rootkits to hide their presence from the operating system, or process hollowing to inject their malicious code into legitimate, trusted processes.

This is why behavior-based detection, a key feature of McAfee security solutions, is crucial for spotting and neutralizing a Trojan before it can cause significant harm.

Most common types of Trojan malware

Trojans come in many forms, each with a different malicious objective. Some of the most prevalent types include: 

  • Backdoor Trojans: Create an entry point for hackers to gain remote control over your device
  • Banker Trojans: Specifically crafted to steal your online banking credentials and financial details
  • Downloader Trojans: Downloads and installs other forms of malware onto your infected system
  • Ransomware Trojans: Encrypts your files and holds them hostage until a ransom is paid
  • Rootkit Trojans: Conceal their presence and other malicious activities, making them exceptionally difficult to detect and remove.

Fake antivirus Trojans: A growing threat

Fake antivirus Trojans, also known as rogue security software or scareware, are malware designed to frighten you into action by displaying alarming, legitimate-looking pop-up messages that claim your computer is heavily infected with viruses. The goal is to trick you into purchasing their full version to remove these non-existent threats. 

If you fall for the scam and enter your payment details, the criminals steal your financial information while the fake software does nothing—or worse, it installs additional malware onto your device. 

To recognize these scams, look for unsolicited, high-pressure warnings, poor grammar, and alerts that appear in your web browser instead of from your actual security program. Never click on these pop-ups or provide payment. Instead, rely on a trusted solution like McAfee, which uses web protection to block the malicious websites and pop-ups that deliver these Trojans, preventing them from ever reaching you.

How Trojans spread across devices

A Trojan usually relies on various distribution methods that trick users into installing it, the most common of which is phishing emails containing malicious attachments or links to compromised websites. Trojans are also frequently bundled with free or pirated software downloaded from untrustworthy sources. Other methods include drive-by downloads, which occur when you visit an infected website, and malicious advertisements, also called malvertising. Trojans can even spread through physical media, such as a compromised USB drive or an infected mobile device to a PC during file sharing. Here’s a closer look at their distribution methods: 

File-sharing sites

Anyone who is a little tech-savvy occasionally uses file-sharing websites such as torrents to download music files, games, and other applications without paying the retail price. These sites are also extremely attractive to hackers who want to find an easy way inside your system. For example, a hacker uploads an unauthorized, Trojan-embedded copy of a popular software to a torrent website for free download, then waits for potential victims to download it.

Email attachments

A hacker sometimes sends generic emails en masse with a Trojan attachment, hoping that you and other recipients will click on it and become instantly infected. At other times, they target specific people or businesses, sending a seemingly legitimate email from someone familiar. The email could contain a safe document, but the virus infects the recipient’s computer the second they open it. If you are a target of such an attack, call the sender—before opening the attachment—to verify they sent this attachment.

Spoofed messages

Hackers often use popular and useful messaging applications to spoof a message so that it looks like it comes from someone you trust. They also create similar usernames and hope you don’t notice the slight differences. Like with fake emails, the hacker is sending you a Trojan-infected file or application.

Infected websites

Many hackers target unsecured websites, preying on the sites’ weaknesses to upload files or even take complete control. The hacker can then redirect you to another malicious site or server that contains the Trojan. Using only trusted, well-known websites is one way to reduce your odds of falling into that trap, but a good antivirus program can also help detect infected and hacked sites.

Hacked Wi-Fi networks

Hacked Wi-Fi networks are also a common source of Trojans and other malware. A hacker creates a fake hotspot network that looks exactly like the one you’re trying to connect to. When you connect to this fake network, the hacker will redirect you to fake websites that look so real that even experts have trouble spotting the difference. These fake websites contain browser exploits that redirect any file you try to download.

How to detect and remove a Trojan

Proactively installing and using a trusted antivirus solution is one of the top ways to get rid of Trojans. Modern security solutions like McAfee go beyond simple signature-based detection. Real-time scanning actively monitors every file and program you access, instantly blocking known threats. These solutions are capable of behavior-based analytics that recognize suspicious, anomalous actions and Trojan signatures to detect, isolate, and then promptly remove them. For example, if a program tries to disable your security software or access sensitive system files, it will be flagged as a potential threat. You can also monitor your system’s security logs and Task Manager for unfamiliar processes or unusual network activity, which can be early indicators of a Trojan infection.

Before removing Trojans, carefully ensure you know which specific programs you’re removing because you could slow, disable or cripple your system if you remove your computer’s key functional programs. 

Trojan removal guide

  1. Disconnect and back up: Immediately disconnect your device from the internet to stop the Trojan from communicating with its operator. Before attempting removal, back up your essential files to an external hard drive or cloud service. This ensures your data is safe in case anything goes wrong.
  2. Enter safe mode: Restart your computer or mobile device in Safe Mode or Safe Boot. This mode loads only the essential operating system files and drivers, which can prevent the Trojan from loading and interfering with its removal.
  3. Run a full antivirus scan: Open your McAfee security software and run a complete, thorough system scan. Antivirus tools are designed to detect, quarantine, and remove malicious files. A comprehensive scan will check every part of your system for the hidden Trojan.
  4. Delete quarantined files: Once the scan is complete, your antivirus will present a list of threats it has found and quarantined. Review the list and allow the software to delete the malicious files. Do not try to manually delete system files you don’t recognize, as this can damage your operating system.
  5. Reboot and verify: After deleting the threats, restart your device in normal mode. Run another full antivirus scan to ensure the Trojan has been completely removed. Your computer’s performance should return to normal.
  6. Secure your accounts: Using a separate, clean device, change the passwords for all your important online accounts, including email, banking, and social media. The Trojan could have captured your credentials while it was active on your system, so assume your old passwords have been compromised.
  7. Notify financial institutions: Contact your bank and credit card companies to warn them of the potential breach. They can place a fraud alert on your accounts and monitor for suspicious transactions.
  8. Monitor your identity: Keep a close watch on your financial statements and credit reports for any unusual activity. Consider enabling identity theft protection services for long-term monitoring and peace of mind.

Proactive & quick tips to stay Trojan-free

Removing Trojans is a great way to safeguard your computer and privacy, but you must also take steps to avoid them in the future:

  • Use a powerful firewall and antivirus: Install a robust security solution as your first line of defense. The McAfee firewall acts as a gatekeeper for your network traffic, while its real-time protection actively scans for and blocks Trojans before they can execute.
  • Practice smart downloading: Only download software and files from official developer websites or trusted app stores. Avoid third-party sites offering free versions of paid software, as these are common hiding places for a Trojan.
  • Adopt a zero-trust email policy: Treat every unsolicited email with suspicion, especially those containing attachments or links. Even if an email appears to be from someone you know, verify with them through a separate communication channel before opening anything.
  • Maintain software update discipline: Regularly update your operating system, web browsers, and all other software. These updates often contain critical security patches that close vulnerabilities exploited by attackers to deliver Trojans.
  • Operate with least-privilege accounts: For your daily computing, use a standard user account instead of an administrator account. This limits a Trojan’s ability to make system-wide changes if it does manage to get through your defenses.
  • Secure your network: Change the default password on your home Wi-Fi router and use a virtual private network (VPN) when connecting to public Wi-Fi to encrypt your data and prevent attackers from intercepting it.
  • Rely on the Cloud. Setup cloud accounts using email addresses that offer account recovery support, and regularly back up your important data to that cloud service. In the case of Apple, you can request assistance to help recover an account.
  • Apply healthy skepticism. Be skeptical of unsolicited emails, especially those with attachments. Never click on suspicious pop-up ads or security warnings.

Real-world examples of notorious Trojan attacks 

History is filled with infamous Trojans that caused widespread damage. 

  • Zeus, also known as Zbot, was a devastating banker Trojan that infected millions of PCs through phishing campaigns. It used keylogging to steal online banking credentials, leading to massive financial losses. 
  • Emotet began as a banker Trojan but evolved into a powerful malware delivery service. It spread via spam emails and was notorious for downloading other dangerous payloads, including ransomware. 
  • TrickBot was a highly adaptable Trojan that harvested financial data, stole credentials, and deployed ransomware across entire networks, making it a persistent danger for businesses and individuals alike.

Stay protected with a trusted solution

Trojans can infect your computer and cause enormous problems before you even know what happened. Once a Trojan gets onto your system, it can monitor your keyboard, install additional malware and cause a variety of other problems you simply don’t want to face. Luckily, most Trojans are generic and easy to handle if you follow this proven process.

Protecting yourself from a Trojan virus doesn’t have to be complicated. By staying vigilant, practicing safe online habits, and understanding how these threats operate, you can significantly reduce your risk. Remember, you’re in control of your digital security. Let this knowledge empower you to navigate the internet with confidence, knowing that comprehensive tools like McAfee+ are always working in the background to provide a powerful shield against threats, ensuring your digital life remains secure.

Our real-time scanning prevents you from downloading malicious files, while our firewall blocks suspicious network communications. Our advanced behavioral detection can even identify and stop new, unknown Trojans based on their malicious actions, providing comprehensive security for your digital life.

The cyberthreat landscape is always changing and evolving. Hackers are always looking for new ways to break into computers and servers, so you must stay updated on the latest threats, and using a proven antivirus solution is always a smart bet. These steps will not only safeguard your devices, but also give you peace of mind while online.