What Is a Trojan Horse?

A Trojan Horse, or simply Trojan, is a type of malware that disguises itself as legitimate software in order to gain access to a computer system. Once installed, Trojans can perform various malicious activities such as stealing sensitive data, monitoring user activity, and providing unauthorised remote access for cybercriminals. Unlike other types of malware, like computer viruses or worms, Trojans do not self-replicate. Instead, they rely on social engineering tactics and user interaction for distribution. For example, they may be hidden within seemingly harmless email attachments or embedded in fake software updates.

To avoid falling victim to Trojans, it’s important to practice safe browsing habits such as avoiding suspicious websites and emails, updating antivirus software, and using strong passwords. It’s equally crucial to recognise signs of a Trojan infection and implement effective removal techniques to prevent further damage to your system.

The concept of a Trojan Horse dates back to ancient Greek mythology, where Greek soldiers hid in a wooden horse to infiltrate and conquer the city of Troy. In terms of cybersecurity, Trojans first emerged in the late 1980s with the PC-Write Trojan. This malware, disguised as a legitimate programme, would delete files on infected computers.

In 1999, Remote Access Trojans (RATs), first appeared. Back Orifice, one of the first RATs was developed by the hacker group Cult of Dead Cow. RAT enabled attackers to remotely control victims’ machines without their knowledge or consent.

Over time, Trojans have evolved into more sophisticated forms like banking Trojans that steal sensitive financial information for extortion purposes. Today’s advanced persistent threats often employ multiple types of malware in coordinated attacks designed to evade detection and maximise damage.

Trojans disguise themselves as valid applications or files to gain access to an individual’s computer system. Once installed, they can cause various types of damage, such as stealing sensitive information, disrupting the system’s performance, or even allowing remote control by cybercriminals.

The primary method Trojans use for infiltration is social engineering. Cybercriminals often employ deceptive tactics like phishing emails and fake software updates to trick users into downloading and installing the malware. In some cases, Trojans may also be distributed through malicious websites or bundled with other seemingly harmless applications.

Once inside the target system, Trojans typically remain hidden from view while performing their malicious activities. They might create backdoors for unauthorised access, modify security settings to avoid detection by antivirus software, or exfiltrate data without raising suspicion. As a result, individuals and organisations must stay vigilant in recognising potential threats and implementing robust cybersecurity measures against them.

Trojan Horse malware comes in various forms, each designed to exploit different vulnerabilities to achieve specific objectives. Some of the most common types of Trojans include:

• Downloader Trojan: This type of Trojan targets a user’s computer to download and install other malicious programmes.
• Backdoor Trojan: Backdoor Trojans provide unauthorised remote access to cybercriminals, allowing them to control the infected computer.
• Banker Trojan: This Trojan is designed to steal sensitive financial information such as bank account details and credit card numbers.
• Infostealer Trojan: Infostealer Trojans are designed to steal sensitive information such as login credentials and personal data.
• Rootkit Trojan: Rootkit Trojans are designed to hide their presence on an infected computer, making them difficult to detect and remove.
• Game-thief Trojan: This Trojan is designed to steal login credentials for online gaming accounts.

Becoming familiar with these types of Trojan malware is essential for understanding potential threats your organisation may face and what technologies and strategies you can leverage to prevent them from infiltrating your systems.

Over the years, various types of Trojan malware have caused significant damage to computer systems and networks. Here are some notable examples:

• Zeus: Also known as Zbot, Zeus is a notorious banking Trojan that steals login credentials and other sensitive data by using keylogging techniques. It resulted in significant monetary losses since being identified in 2007.
• CryptoLocker: This infamous ransomware emerged in 2013 and encrypts victims’ files until they pay a ransom. The CryptoLocker Trojan was distributed through email attachments and compromised websites, causing widespread disruption.
• Dyre/Dyreza: Another banking Trojan similar to Zeus, Dyre or Dyreza gained notoriety for targeting high-profile organisations with spear phishing campaigns. By intercepting web traffic between users and banks, it stole login information to access accounts directly.

Besides these well-known examples, many other types of Trojans continue to emerge regularly. Understanding how they work can help you recognise potential cyber-attacks before they cause harm to your system or network.

Detecting Trojan Horses can be challenging, as they often disguise themselves as legitimate software. However, certain signs may indicate a Trojan Horse on your computer. By being vigilant and aware of these warning signs, you can take action before significant damage is done.

• Unexpected system behaviour: If your computer starts behaving erratically or experiences frequent crashes, it could indicate a Trojan infection.
• Slow performance: A sudden decrease in system performance might signal the presence of malware consuming resources.
• New files or programmes: Unfamiliar files or programmes appearing on your computer without user action could be due to a Trojan Horse installation.
• Suspicious emails and attachments: Be cautious when opening emails from unknown senders or unexpected attachments; these malicious attachments could contain malicious code programmed to infiltrate your system.
• Abrupt changes in security settings: Trojans may attempt to disable security features such as firewalls and antivirus software. If you notice changes in settings that you did not authorise, investigate further for potential threats.

Consider using reputable antivirus software with real-time scanning functionality to enhance detection capabilities. This helps identify and neutralise potential threats before they harm your system.

Removing a Trojan Horse from your system requires a combination of best practices and proper tools. Follow these steps to eliminate the threat:

1. Update your antivirus software: Ensure you have the latest version of antivirus software, as it contains updated definitions to detect and remove new threats.
2. Disconnect from the Internet: To prevent further damage or data theft, disconnect your device from networks while removing the malware.
3. Safely boot into Safe Mode: Restarting in Safe Mode allows you to run essential programmes without interference from malicious processes. Press F8 during startup for Windows systems or hold Shift during a restart on macOS devices.
4. Delete temporary files: Clearing out temporary files can help speed up virus scanning and potentially remove some malware components. Use Disk Cleanup on Windows or Finder’s “Empty Trash” feature on macOS.
5. Run an antivirus scan: A comprehensive system scan using reputable antivirus software should identify and quarantine any Trojans present on your device.

To prevent Trojan malware from infecting your system, use strong passwords, maintain up-to-date antivirus protection, and avoid downloading and installing malicious applications, especially from unfamiliar emails. These practices are essential even if you have robust cybersecurity systems and security awareness training implemented throughout your organisation.

You must implement a multi-layered security approach to safeguard your systems from Trojans. Here are some effective strategies for protecting against Trojan malware attacks:

• Install reputable antivirus software: Choose a reliable antivirus programme that offers real-time protection and regular updates.
• Keep software up-to-date: Regularly update all applications and operating systems with the latest patches to close vulnerabilities cybercriminals may exploit.
• Avoid suspicious downloads: Be cautious when downloading files or clicking on links from unknown sources. Always verify the legitimacy of websites before proceeding with downloads.
• Educate users about phishing attacks: Train employees to recognise and avoid potential phishing emails, which often serve as an entry point for Trojan malware.
• Create strong passwords and enable multifactor authentication (MFA): Use complex passwords combined with multifactor authentication, making it more difficult for attackers to gain unauthorised access to accounts or devices.

In the world of cybersecurity, it takes more than just understanding what a Trojan Horse is. It’s just as critical for IT teams, security professionals, and enterprise leadership to deploy the right cybersecurity technologies and safeguard strategies to prevent these invaders from wreaking havoc on an organisation’s data and systems.

Proofpoint offers a comprehensive suite of Advanced Threat Protection (ATP) solutions to safeguard your organisation from Trojan Horse malware and other cyber threats. Proofpoint’s advanced Email Protection Services help teams effectively detect, block, and remediate malicious emails that may contain Trojans.

Additionally, Proofpoint’s suite of solutions to help combat Trojans includes:

• Email Security: Using machine learning algorithms, Proofpoint’s Email Security and Protection solution identifies suspicious emails containing potential Trojans before they reach users’ inboxes.
• Sandboxing: The integrated sandboxing technology analyses unknown files in a safe environment to identify hidden malicious code or behaviour associated with Trojan Horses.
• Data Loss Prevention (DLP): Proofpoint’s enterprise DLP solution prevents sensitive data leakage by monitoring outbound communications for potential exfiltration attempts by active Trojans within your network.
• Security Awareness Training: To reduce the risk of employees falling victim to phishing attacks or inadvertently downloading Trojans, Proofpoint provides an effective Security Awareness Training programme.

In addition to these features, we continuously update our threat intelligence database with information on emerging malware strains and attack vectors. This ensures that our ATP solutions remain at the forefront of cybersecurity defence against evolving threats like Trojan Horse malware. For inquiries or more information, contact Proofpoint.