trojan virus

What Is a Trojan Virus?

A Trojan virus is a form of malware that manipulates a computer user into thinking content in a file is safe. It is often referred to as a Trojan horse like the wooden horse used by the Greeks to trick the Trojans, the file appears familiar, but the inside is harmful. A trojan virus leaves a machine vulnerable to a range of threats.

Common types of Trojan viruses

Backdoor Trojans

The most common type of Trojan virus, the backdoor trojan accesses the machine remotely and allows hackers to gain control and upload, download, or delete files for financial gain. They can also upload damaging software that can affect the machine’s power.  

Exploit Trojans

Exploit Trojans is a malware programme that contains code or data that is used against a machine to exploit specific vulnerabilities and weaknesses within an application or computer system. The hacker will target victims through methods like phishing attacks.

Rootkit Trojans

Rootkit trojans are hidden in plain sight. They are disguised as normal files so that anti-virus and anti-ransomware software overlooks them. It enables administrator-level access to a computer or computer network and the main intention is to steal the identity information from the computer and gain control of a system. These can sometimes be hardest to deal with because it’s difficult to detect and remove.  

Banker Trojans

Designed to gain access to confidential and/or material information stored or processed through online banking, Banker trojans are malicious computer programmes. It is built with a backdoor and allows outside parties to gain access to a machine. In some cases, they copy bank client’s credentials by parodying a financial institution’s login webpage. Once copied, they can make unauthorised transactions, steal identities and withdraw funds to attackers’ accounts.  

The main target for these trojans is personal information used for banking and online shopping.

Distributed Denial of Service (DDoS) Trojans

DDoS’ are malicious applications designed to attack a service or website with the intention of overwhelming it with false traffic and/or fake requests.

Downloader Trojans

A Trojan downloader may appear harmless at first glance, but it has the potential to cause havoc on devices once infiltrated. These Trojans operate by fetching and installing malicious software onto a computer from distant servers or websites. While a Trojan virus downloader may seem distinct from a typical Trojan, its ultimate objective remains unchanged: to cause harm, steal data, and expose your personal information.

Spotting a Trojan virus

Similar to most computer virus infections, systems that are infected with a Trojan virus can display many telling symptoms. Here are the main ones to look out for:

  • Slower than usual
  • Unauthorised applications are appearing
  • System crashes and freezes
  • An increased number of internet redirects
  • Frequent pop-ups  
  • Applications won’t start

If you believe you have a Trojan virus, you should first search through the programmes and applications and check that you installed them all and if there are any unrecognised ones. This is the same for files and documents. If you find anything unusual, you should report this to your IT department who can run the necessary checks and scans.

Protecting your computer

To safeguard against a wide range of cyber threats, it's essential to adopt a multi-layered cyber security strategy. In addition to implementing a robust security solution, educating users about these cyber threats stands out as one of the most critical steps you can take.

Always remember:

  • If you are unsure about the trustworthiness of a software or a file source, don’t click or download it.
  • Be wary when opening an attachment within an email that you are wary of or is from someone you don’t know.
  • Always ensure your computer and mobile are up to date with the latest software.
  • Make sure that anti-virus software is installed and operational on your computer.

Sharp offer a range of cyber security options from complete security audits and back up and disaster recovery to firewall protection.  

Learn more about Sharp’s Cyber Security Solutions here.