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Trojan Horse Viruses - History, Types, and How to Protect Yourself

Trojan Horse Viruses - History, Types, and How to Protect Yourself

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What is Trojan Horse?

Trojan Horse is a type of malware.  Malicious software of this type masquerades as legitimate software to hack computers. Trojan prefers to operate discreetly and establishes security backdoors via which other infections can enter the system.

The trojan is designed to gain unauthorized distant access to a computer. Trojan viruses, unlike viruses, do not propagate by invading additional files on computers. Instead, Trojan typically goes unseen, sitting silently in your computer gathering data or putting up security rules. 

An attacker conceals a harmful application in a seemingly harmless email or download. The application sends the virus to the victim’s device with a single click or download, and the malicious code can then perform whatever task the attacker has planned. Once transferred and active, the Trojan virus can have a detrimental impact on performance and put the victim at risk.

Trojan malware can provide an attacker with backdoor access to a device to record keystrokes or steal sensitive user data, install a virus or worm, encrypt user data, activate a device’s camera or recording capabilities, or transform the computer into a zombie computer to commit fraud or unlawful acts.

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History of Trojan Horse

One of the most well-known battle tactics is the Trojan Horse. The Trojan Horse virus is named after the famous tale of the Trojan War. According to Greek mythology, the Greeks presented the Trojans with a big wooden horse as a farewell gift. The Trojans brought the horse inside the city walls. The Greek troops hidden in the horse climbed out and opened the city gates, allowing the Greek army to conquer the city. The Trojan Horse’s meaning is the same as in the tale.

How does a Trojan Horse Virus work?

Below is an example of a Trojan Horse virus:

  • The user must install malicious software or click on a bogus link. Typically, social engineering approaches are used to persuade users to click on such links.
  • The download option will usually appear as a pop-up, banner ad, or website link.
  • In order for the assault to launch on the system, the deceptive application must be installed as an executable file.
  • The user clicks on the link, believing it to be beneficial software, from an unknown source on an untrustworthy website.
  • The Trojan server will run automatically each time the computer is switched on.
  • Trojan can provide the attacker with backdoor access to a device.

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Types of Trojan Horse Virus

Trojan-downloader

This is a virus that unintentionally downloads and installs other infections.

Trojan droppers

Cybercriminals employ these complicated programs to install the software. Because most antivirus products do not recognize droppers as malicious, they are commonly used to spread malware.

Ransomware

It is a Trojan, Trojan-ransom, that encrypts data on your computer or device. The crooks in charge of the ransomware would demand a payment in exchange for the decryption key. Without the decryption key, recovering the data is extremely difficult. Recent ransomware outbreaks include WannaCry and Petya.

Users should adopt a rigorous and systematic backup and recovery process according to cybersecurity experts.

Trojan-banker

This type of Trojan virus specifically targets personal information used for banking and other online transactions. The attacker can remotely access the Trojan.

Trojan rootkit

This type of Trojan malware is intended to prevent the discovery of malware that is already infecting a system so that maximum damage can be inflicted to your workstation. Rootkits are also used to enroll the victim’s device as part of a botnet.

Trojan backdoor

It is a popular type of Trojan. This type of Trojan Horse virus allows hackers to remotely access and control a computer, often for the purpose of uploading, downloading, or executing files at will. Some Trojan can send premium SMS, steal your instant messaging credentials, spy on system activities to capture keystroke data and steal email addresses and gaming credentials. It is also called a remote access Trojan (RAT.)

Spy Trojan

Spyware is malware that collects data from your computer. So far, when you are using a device that is connected to the internet, this Trojan can convey your personal and confidential information to a user with nefarious intentions.

Keylogger

Keylogger is software that is meant to hide gaze or operations in your computer. A keylogger’s main objective is to hide hazardous applications from detection, allowing them to run for an extended period of time on infected machines.

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How to Identify a Trojan Horse Attack

Emails with dangerous links or attachments are sent by cybercriminals; the users are then duped by appealing adverts and offers, and their devices are infected with a Trojan virus as soon as they open the attachment or click on the link. Because Trojan is used to spreading a variety of different types of malware, you should check for many of the same telltale indicators of malicious software if you suspect that your device has been hacked by one.

The indicators  may include the following:

Poor device performance

If your computer or mobile device is running slowly or crashing more frequently than normal

Strange device behavior

Programs running without your initiation or other unexplained processes being executed on your device

Pop-up and spam interruptions

Are you noticing an uptick in the number of interruptions from browser and pop-ups or email spam?

If your device is exhibiting these symptoms, it is possible that a Trojan virus has managed to sneak its payload onto your device.

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Impact of Trojan Horse Virus

These are the effects when you encounter a Trojan:

  • Deletes, modify, blocks data stored in a computer
  • Disrupts the performance of target computers or networks
  • A surge in pop-ups—not only advertisements but also internet pop-ups, advertising items, or antivirus scans that, when opened, install a virus into your system.

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Protection against Trojan Virus

There are a few steps to help you recognize and get rid of the Trojan virus.

  • Never download or install software from a source that you do not trust completely.
  • Never open an attachment or run a program sent to you in an email from someone you do not know.
  • Keep all software on your computer up to date with the latest patches.
  • Install a good antivirus.

How to Remove Trojan Horse

Try searching your computer for any programs or applications that you do not remember installing yourself. Enter any unrecognizable file names or programs into a search engine to determine if they are recognized as Trojan.

 Steps to remove Trojan virus

Let us take a look at a few measures to remove Trojan Horse:

  • If a Trojan infection is found, the computer should be unplugged from the internet and the suspicious files should be eliminated using antivirus software or by reinstalling the entire operating system.
  • The presence of a Trojan can be detected by a dynamic link library (DLL) error, which indicates the presence of tainted files. The error message specifies which exe file is corrupted.
  • Turn off the system restore function; this aids in the complete eradication of computer viruses.
  • Users must restart the computer and hit the F8 key to enter safe mode.
  • Go to the Control Panel and click on Add or Remove Programs. By gaining access, suspect files can be permanently erased from the system.
  • Restart the computer and change the settings from safe to normal mode. This process removes viruses.

Conclusion

The trojan is a sort of malware. The trojan is a computer program that is meant to acquire unauthorized remote access to a computer. Trojan computer virus is a dangerous malware. With a single click or download, the program transfers the virus to the victim’s device, where the malicious code can then carry out whatever operation is intended by the attacker. Trojan creates backdoors that allow the attacker to carry on with their malicious intentions. We can secure our PCs by installing antivirus software, keeping our software up to date, and avoiding clicking on unfamiliar links and email attachments.

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About the Author

Lead Penetration Tester

Shivanshu is a distinguished cybersecurity expert and Penetration tester. He specialises in identifying vulnerabilities and securing critical systems against cyber threats. Shivanshu has a deep knowledge of tools like Metasploit, Burp Suite, and Wireshark.