What Are Trojans?

A Trojan (AKA Trojan horse) is a type of malware that infiltrates devices by disguising itself as a legitimate file or software. Designed to gain access to a user’s system, Trojans allow threat actors to perform various harmful activities on a user’s device without their knowledge. Trojans are deceptive as they trick users into installing them by hiding in infected versions of known and valuable software, such as popular games, productivity tools, security updates, and more.

How Trojans Work

Trojans prey on users who lack security awareness with several methods of infecting devices. The malware is embedded in apps, programs, pop-up sites, emails, files, or other attachments that appear to be safe to open and interact with—e.g., threat actors may send emails with malicious attachments that seem authentic, but include files that propagate malware. Once opened, the attachments install a Trojan server client on the user’s device, providing the threat actor with access. Threat actors also plant Trojans by employing social engineering techniques such as spoofing and phishing, posing as trustworthy individuals or organizations.

With a remote access Trojan (RAT), threat actors can attack devices from a remote location without interrupting the user’s operations or exposing themselves. Trojan servers self-launch each time an infected device is powered on, and they can self-delete, revert to dormancy, or continue being active on the system depending on the kind of Trojan and its purpose. 

Trojans are used for various reasons, such as: 

  • Monitor user activity
  • Steal financial information
  • Modify sensitive data
  • Damage or delete files
  • Control a user’s device
  • Spread more malware across a network

Common Types of Trojans

Threat actors use various types of Trojans to launch digital attacks. These are the most common types of Trojans.

Backdoor Trojan: A Trojan that provides complete control over devices by allowing threat actors unauthorized backdoor access into otherwise protected endpoints. Backdoor Trojans are widely used to enhance the capabilities of botnets.

Downloader Trojan: A Trojan that downloads and installs harmful applications or malware on target endpoints, e.g., adware that monitors user activities. 

Ransom Trojan: These Trojans slow down computer systems and restrict users from accessing their data or using their device effectively. The target is held hostage until a ransom is paid to repair the data and restore normal use.

Fake Antivirus Trojan: Simulating the behaviors and functions of legitimate antivirus software, fake antivirus Trojans detect nonexistent cyber threats on a user’s device, which threat actors leverage to extort money from the user to remove the fake threats.

Banking Trojan: This Trojan’s purpose is to steal financial data. The banking Trojan seeks to gain access a user’s credit and debit card information or online banking accounts.

Trojans vs. Viruses

Trojans and viruses are both created with harmful intentions but materialize differently. Trojans attack a user’s system unnoticed, not typically interfering with the normal operating state of a target system. While Trojans are designed to initiate remotely controlled cyberattacks, they cannot self-replicate. Any attempt to spread Trojans requires human intervention. 

Viruses, on the other hand, are less covert. They’re deployed to disrupt systems and cause major issues, making a device unusable for the target user. They can reproduce and travel swiftly across the network, but they cannot be controlled remotely. 

How to Detect Trojans

Trojans are not always easily detectable due to the hidden nature of their invasive tactics. However, there are certain telltale signs that the malware might have infiltrated a network:

Slow device performance: Trojans consume memory resources and cause instability, which can cause systems to slow down and freeze. If computers or devices are abnormally sluggish and crashing frequently, the system may be infected with Trojans. 

Unauthorized behavior: The random appearance of unfamiliar apps, files being deleted or changed without authorization, and other unexplained movements could indicate that the network is being controlled by Trojans.

Increase in pop-up ads and unwanted interruptions: An increase of interruptions from browser pop-ups or email spams can point to an infected network. Trojans can redirect browsers to unfamiliar, malicious sites, and alter search results.  

Disabled security software: Trojans will try to bypass or disable software to remain hidden. If security software has been disabled, or refuses to open, it could be a sign that Trojans have invaded the network.

How to Prevent Trojans

Pairing responsible online behavior with robust cybersecurity solutions is an effective way to prevent Trojans. 

System updates and patching

Installing system updates can immediately fix security flaws on a device. Exploiting security loopholes is a common tactic that Trojans use to spread across a network, so patching any vulnerabilities can eliminate security flaws.

Deploy Endpoint Security

Endpoint security solutions safeguards all devices that connect to the corporate network, helping systems stay secure. By deploying endpoint security, organizations can proactively detect, block, and mitigate risks posed by Trojans.

Employ Zero Trust Network Access

Zero Trust Network Access (ZTNA) is a security solutions that minimizes the risk of unauthorized access within a network by assuming that no user or device should be trusted. Users must verify and authenticate themsevles to access any resource, reducing the possibility of infiltration.

Robust security awareness training

Rigorous security awareness training is vital to ensuring the prevention of Trojans. By educating employees of potential cybersecurity risks and best practices, organizations can foster a cyber resilient culture and equip users with the necessary training and skills to identify and protect against Trojans.

As a human-centric subscription-based 24x7x365 Managed XDR service, CylanceGUARD® provides the expertise and support businesses need to prevent and protect against ransomware attacks. CylanceGUARD combines the comprehensive expertise embodied by BlackBerry Cybersecurity Services with AI-based Endpoint Protection (EPP) through CylanceENDPOINT. In short, CylanceGUARD provides business with the people and technology needed to protect the enterprise from the modern threat landscape.