What Does 'Trojan (Trojan Horse)' Mean?

What is a Trojan (Trojan Horse)?
Photo by Tayla Kohler on Unsplash

A Trojan horse, or Trojan, is a type of malicious software that is designed to deceive users into believing it is legitimate while actually performing undesirable or harmful actions on their systems. Trojans are often disguised as genuine software or attachments and are typically spread through email, social media, and online file sharing.

The name “Trojan horse” comes from the ancient Greek story of the Trojan War, in which the Greeks gifted a giant wooden horse to the Trojans as a peace offering, but the horse was indeed filled with soldiers who, once inside the city, opened the gates and allowed the Greek army to attack and conquer Troy.

Similarly, a Trojan horse appears to be an authentic program or file, but in reality it contains hidden malware that can perform various harmful actions on a user’s system.

There are several different types of Trojans, each with its own specific purpose and method of operation.

Some common types of Trojans include:

Backdoor Trojans: These Trojans allow a person to gain access to a user’s system and remotely control it, usually without the user’s knowledge. Backdoor Trojans can be used to download and install other malware, steal sensitive data, and perform other damaging actions.

Banking Trojans: These Trojans are developed to steal login credentials and other sensitive information, such as credit card numbers and bank account passwords. Banking Trojans are typically spread through phishing emails or websites that mimic legitimate financial institutions.

Ransomware Trojans: These Trojans encrypt a user’s data and demand a ransom be paid in exchange for the decryption key. Ransomware Trojans can cause significant monetary losses and disruption for individuals and organizations.

Infostealer Trojans: These Trojans are created to steal personal information, such as login credentials and passwords, from a user’s system. Infostealer Trojans can also be used to gather sensitive data, such as financial details, and transmit it to the attacker.

Rootkit Trojans: These Trojans are meant to gain access to a computer’s administrative privileges, allowing the hacker to control the machine and install other malware. Rootkit Trojans are particularly difficult to detect and remove because they can operate at a low level within the computer, below the operating system’s surface.

Trojans can have a range of impacts on a user’s system, depending on their specific design and purpose.

Some common effects of Trojans include:

Loss of personal data: Trojans can be used to steal sensitive information, such as login credentials, financial data, and personal documents.

Loss of system control: Backdoor Trojans can allow an invader to remotely control a user’s system, potentially installing other malware or performing malicious actions.

Financial losses: Banking Trojans can be used to steal information and make unauthorized transactions, leading to financial losses for the victim. Ransomware Trojans can also cause monetary losses by demanding a ransom in exchange for the decryption key.

Disruption of system operations: Trojans can cause a lot of issues with system performance, including slowdowns, crashes, and loss of access to certain functions or files.

There are several ways that users can protect themselves from Trojans.

Some best practices include:

Keeping software and operating systems up to date: Trojans may exploit vulnerabilities, so installing updates and patches can help.

Using reputable antivirus software: Antivirus software can help detect and eliminate Trojans as well as other types of malware.

Being careful with emails and online downloads: Avoid opening emails or downloading attachments from unknown sources, and be wary of links in emails or on websites.

Being cautious when using social media and online file sharing: Be careful about clicking on links or downloading files from social media or file sharing websites, as these can be common sources of Trojans.

Using strong and unique passwords: Using strong, distinct passwords for all accounts can help protect against Trojans that may try to steal login credentials.

Using a firewall: A firewall can help block incoming traffic from potentially dangerous sources, including Trojans.

Being careful when using public Wi-Fi: Public Wi-Fi networks can be less secure, so be vigilant when accessing sensitive information on these networks.

How the Trojan Infects Your System

Trojans are frequently delivered through email attachments, downloads from the internet, or through online advertisements. Once a Trojan is activated on a victim’s device, it can do many bad things, like steal sensitive information, install more malware, or let an intruder take control of the victim’s device remotely.

One of the most common ways that Trojans are delivered is through phishing emails. These are fraudulent emails that appear to be from legitimate sources, such as banks, government agencies, or well-known companies.

The emails may contain a link that, when clicked, downloads the Trojan onto the victim’s device. Alternatively, the email may contain an attachment that, when opened, activates the Trojan.

Another way that Trojans are delivered is through downloads from the internet. These may be downloads of pirated software, music, or movies, or they may be downloads of legitimate software from websites that have been compromised by attackers. In either case, the downloaded file will contain the Trojan, which will be activated when the victim installs the software.

Online advertisements are another common method of delivering Trojans. Criminals may create fake advertisements that, when clicked, download the Trojan onto the victim’s device.

These advertisements may be displayed on legitimate websites or on websites that have been created specifically for the purpose of delivering Trojans.

Malicious actions

Once a Trojan is activated on a victim’s device, it can perform a variety of malicious actions. One common action is to steal sensitive information, such as login credentials, financial information, or personal identification numbers (PINs). The hacker can then use this information to gain access to the victim’s accounts or to steal money.

Another common action of Trojans is to install additional malware onto the victim’s device. This may include viruses, worms, or other types of malware that can further compromise the device and allow the criminal to gain more control.

Trojans may also allow a person to gain remote access to the victim’s device. This can be done through a “backdoor” that the Trojan creates on the victim’s device.

Once the attacker has gained access, they can perform various actions on the victim’s device, such as modifying files, monitoring activity, or stealing information.

How to protect against Trojans

To protect against Trojans, it is important to follow best practices for online security. This includes being alert when opening emails and attachments, avoiding downloading files from untrusted sources, and keeping your operating system and antivirus software up to date.

It is also a good idea to use a firewall to block incoming connections from suspicious sources.

In addition, you can use antivirus software to detect and remove Trojans. Antivirus software works by scanning your device for known Trojan viruses and quarantining or deleting them. It is vital to keep your antivirus software up to date, as new Trojans are constantly being developed and released.

How to remove a Trojan Horse

If you think you may have a Trojan on your device, there are several steps you can take to get rid of it. First, try running a full scan with your antivirus software. If the Trojan is detected, the software should be able to remove it. If the Trojan is not detected, you may need to use a specialized Trojan removal tool.

These tools are made especially to detect and delete Trojans, and they may be able to identify Trojans that your antivirus software misses.

If you are unable to eliminate the Trojan using antivirus software or a specialized removal tool, you may need to manually remove the Trojan. This can be a complex process, and it is necessary to be careful as you do so, as you do not want to accidentally delete important system files.

To manually delete a Trojan, you will need to identify the specific Trojan that is on your device. This may require some research, as there are many different types of Trojans, each with its own individual characteristics.

Once you have identified the Trojan, you will need to locate and delete the files that are associated with it. This may include the original executable file that was used to install the Trojan as well as any additional files that the Trojan has created.

It bears mentioning that manually removing a Trojan can be a difficult and time-consuming process. If you are not comfortable with this process, it is best to seek the help of a professional.

Furthermore, it is essential to remember that even if you are able to remove the Trojan, your device may still be at risk for future attacks if you do not take steps to improve your online security.


Trojans are a significant threat to both individuals and organizations, and it is key to take steps to protect against them. By following good practices and using appropriate security measures, users can help reduce the risk of falling victim to a Trojan attack.

Keep in mind that Trojans do not replicate or spread on their own, like viruses or worms. Instead, they rely on the victim to inadvertently download and install them. This is why it is crucial to be wary when opening emails, downloading files, and clicking on advertisements, and to use antivirus software and firewalls to protect your device.