What Are Trojans in Cybersecurity? 15 Types of Trojan Malware Explained (2025 Guide)

Table of Contents

• How Does a Trojan Horse Actually Work?
• Why Are Trojans Still a Big Deal in 2025?
• Fast Reference: Major Trojan Categories and Their Typical Goals (2025 Edition)
• What Are the 15 Most Common Types of Trojans?
• Real‑World Case Study (2024) – “Anatsa” Mobile Banker
• How Can You Defend Against Multiple Trojan Types?
• Key Takeaways
•  Frequently Asked Questions (FAQs)

Cyber‑criminals have endless tricks, but Trojans remain their all‑time favorite. Named after the legendary Greek ruse, a Trojan Horse looks harmless — a free game, a “critical” software patch, an invoice PDF — yet hides malicious code that opens the gates for attackers. Unlike viruses or worms that self‑replicate, a Trojan needs a bit of social engineering to persuade you to run it first. Once inside, it can steal data, spy on you, encrypt your files, launch DDoS attacks, or even recruit your device into a botnet.

Below you’ll find a 360° guide to how Trojans work, why they thrive in 2025, and a deep dive into every major type you’ll meet in the wild. Feel free to jump to the section that answers your immediate question.

How Does a Trojan Horse Actually Work?

1. Bait – Attackers craft an enticing lure: cracked software, a phony “urgent” email attachment, or a fake app on a third‑party store.

   
   

2. Execution – The user downloads and runs the file, granting the Trojan the same privileges as the logged‑in account.

3. Payload Delivery – Hidden code silently drops additional malware, modifies registry keys, or contacts a command‑and‑control (C2) server.

4. Persistence – The Trojan embeds itself (e.g., as a Windows service or Launch Agent on macOS) so it survives reboots.

5. Action on Objectives – That could be keylogging, data exfiltration, ransomware encryption, cryptomining, or backdoor creation for future exploits.

Key takeaway: A Trojan cannot infect without user action — but cleverly designed social‑engineering makes that action surprisingly likely.

Why Are Trojans Still a Big Deal in 2025?

• Work‑from‑anywhere culture means employees are mixing personal and corporate devices, expanding attack surfaces.

• AI‑generated phishing boosts realism, helping Trojans bypass human suspicion and even some secure email gateways.

• Modular malware kits for sale on dark‑web marketplaces let low‑skill attackers spin up tailored Trojans in hours.

• Cryptocurrency wallets on both phones and PCs are lucrative targets, keeping banker and clipper Trojans popular.

 Fast Reference: Major Trojan Categories and Their Typical Goals (2025 Edition)

What Are the 15 Most Common Types of Trojans?

Below we unpack each category, explain its tactics, and note fresh defensive moves for 2025.

1. Backdoor Trojan

A Backdoor Trojan secretly opens a network port or uses a web‑based command‑and‑control channel so attackers can revisit your device whenever they wish.
Hot defense tip (2025): Use EDR solutions that flag unsolicited outbound traffic, and enforce egress‑filtering firewall rules.

2. Banker Trojan

Banker Trojans (a.k.a. credential‑stealers) watch login forms, intercept web sessions, or overlay fake login windows—especially on mobile banking apps.
Defense: Enable hardware security keys (FIDO2) and use bank‑supplied official apps from trusted stores only.

3. Downloader / Dropper Trojan

These “stage‑one” payloads are tiny but dangerous—they silently fetch a second‑stage malware such as ransomware.
Defense: Block outbound traffic to newly registered domains; sandbox suspicious attachments before delivery.

4. RAT (Remote Access Trojan)

A RAT Trojan gifts the attacker near‑total desktop control (screen share, file transfer, webcam). Popular in corporate espionage.
Defense: Monitor for abnormal RDP, VNC, or custom viewer processes; audit user‑behaviour analytics for anomalies.

5. SMS Trojan

Mostly Android‑focused, SMS Trojans send premium‑rate texts or intercept MFA codes.
Defense: Keep Play Protect on, sideload with caution, and review default SMS permissions for new apps.

6. DDoS Trojan

Turns devices into a botnet node to flood targets with traffic. IoT is a prime victim due to weak default passwords.
Defense: Change factory creds, disable UPnP, and patch IoT firmware promptly.

7. Ransomware Trojan

Drops an encryption engine, then demands cryptocurrency. Many 2025 strains now steal data first (“double extortion”).
Defense: Maintain offline or immutable backups, invoke zero‑trust segmentation, and patch VPN appliances.

8. Spyware Trojan

Steals keystrokes, screenshots, clipboard, mic audio. High‑end variants like “Pegasus” exploit zero‑click phone vulnerabilities.
Defense: Keep OS fully updated; enable Lockdown Mode on iOS for high‑risk individuals.

9. Rootkit Trojan

Installs deep into kernel or firmware to hide malware processes.
Defense: UEFI Secure Boot, TPM‑based integrity checks, and firmware‑level attestation.

10. Fake AV Trojan

Shows false infection warnings, then demands payment for “full clean.”
Defense: Educate users on legit AV UI, block rogue download sites, and use browser extension reputation checks.

11. Adware Trojan

Bombards you with pop‑ups, redirects search queries, collects tracking data.
Defense: Harden browsers, block malicious extensions, employ DNS‑level ad filtering (e.g., Pi‑hole).

12. Game‑Thief Trojan

Targets Steam, Epic, or console credentials, plus rare in‑game skins worth resale.
Defense: Enable platform 2FA, avoid cheat mods, scan downloaded archives.

13. Clipper Trojan

Monitors clipboard and swaps crypto wallet addresses to steal funds during transactions.
Defense: Double‑check wallet string before sending; use QR codes or hardware wallets.

14. Proxy Trojan

Converts your machine into an exit node criminals resell for anonymity.
Defense: Detect unexplained high outbound traffic; block unknown proxy software installations.

15. IoT Trojan

Targets smart TVs, cameras, fridges—anything with weak or hard‑coded credentials—to recruit them into wider attacks.
Defense: Network‑segment IoT devices from critical systems and disable remote management.

Real‑World Case Study (2024) – “Anatsa” Mobile Banker

• Vector: Malicious dropper apps posed as QR code readers on Google Play.

• Impact: In five EU nations, over €11 million stolen via automated money‑transfer systems.

• Lesson Learned: Even official app stores aren’t immune. Mobile EDR and real‑time device posture assessments are now table stakes for enterprise BYOD programs.

How Can You Defend Against Multiple Trojan Types?

1. Zero‑Trust Architecture – No implicit trust inside the LAN; every request must authenticate and validate.

2. Behavioral EDR – Detects anomalous process behavior, not just known signatures.

3. Least‑Privilege & Application Whitelisting – Users run as standard accounts; only approved apps can execute.

4. Security Awareness Training – Continuous micro‑learning on phishing red flags and safe download habits.

5. Regular Backups + Incident Response Playbooks – So ransomware or wiper Trojans don’t become business‑ending events.

Key Takeaways

• Trojans thrive on human curiosity and outdated defenses.

• There are 15 core Trojan families every defender (and end‑user) should recognize.

• Proactive measures—patching, zero‑trust, EDR, and user education—cut risk dramatically.

FAQ:

What is a Trojan in cybersecurity?

A Trojan is a type of malware that disguises itself as legitimate software to trick users into executing it, allowing attackers to gain control or steal information.

How does a Trojan work?

A Trojan relies on the user to install or run it. Once executed, it can perform various malicious actions like stealing data, installing other malware, or giving remote access to attackers.

What are the main types of Trojans?

There are several types including backdoor Trojans, banker Trojans, RATs (Remote Access Trojans), spyware, ransomware Trojans, and more.

What is a backdoor Trojan?

A backdoor Trojan creates a hidden path into a system, allowing attackers to access and control the device without user knowledge.

How do banker Trojans steal information?

Banker Trojans focus on financial theft by stealing online banking credentials or overlaying fake login forms on banking apps and websites.

What does a Remote Access Trojan (RAT) do?

RATs enable attackers to fully control an infected system, including its screen, keyboard, files, microphone, and webcam.

How do ransomware Trojans operate?

They encrypt the user’s data and demand a ransom, typically in cryptocurrency, for the decryption key.

Are Trojans viruses or worms?

No. Trojans require user interaction and do not replicate themselves like viruses or worms.

What is a downloader Trojan?

Downloader Trojans are lightweight malware programs that download and install additional malicious software onto the victim’s system.

Can a Trojan infect smartphones?

Yes. Mobile Trojans often target Android devices by hiding inside malicious apps or fake software updates.

What is an SMS Trojan?

An SMS Trojan sends premium-rate messages from an infected device or intercepts SMS messages such as 2FA codes.

How do spyware Trojans work?

Spyware Trojans collect sensitive data such as keystrokes, browsing history, or even audio and video feeds from the infected system.

What is a clipper Trojan?

Clipper Trojans monitor the clipboard for cryptocurrency wallet addresses and replace them with the attacker’s wallet address.

What is a fake antivirus Trojan?

This Trojan pretends to be antivirus software, displays fake alerts, and tricks users into paying for unnecessary or fake fixes.

How do adware Trojans spread?

Adware Trojans are often bundled with free software and bombard users with unwanted ads, pop-ups, or redirects.

What is a rootkit Trojan?

Rootkit Trojans hide malicious processes deep within the system, making them hard to detect by traditional antivirus tools.

Are Trojan attacks increasing in 2025?

Yes. Trojans are evolving with AI-driven phishing, modular payloads, and better evasion techniques, making them more dangerous than ever.

How do Trojans spread?

They spread through phishing emails, fake software downloads, infected USB devices, and malicious websites.

Can Trojans bypass antivirus?

Yes. Advanced Trojans may use encryption, code obfuscation, or zero-day vulnerabilities to evade traditional antivirus tools.

What is a DDoS Trojan?

It infects systems and uses them to launch Distributed Denial of Service attacks, flooding target servers with traffic.

What is a proxy Trojan?

Proxy Trojans hijack the victim's bandwidth and sell it to proxy networks, making the user’s IP address part of a larger anonymous traffic system.

What is an IoT Trojan?

IoT Trojans target smart devices like cameras, routers, and thermostats, often enlisting them in botnets for coordinated attacks.

How to detect Trojan malware?

Use behavioral analysis tools like EDR, monitor for unusual network activity, and regularly scan systems with updated security software.

How to remove a Trojan?

Run a full system scan using trusted anti-malware tools, boot into Safe Mode if needed, and consider restoring from a clean backup.

What is a game-thief Trojan?

These Trojans steal gaming credentials, rare items, or in-game currency from platforms like Steam, Xbox, or PlayStation.

How to prevent Trojan infections?

Avoid downloading unknown files, keep your system updated, use antivirus/EDR, and train users to recognize phishing threats.

Are all Trojans harmful?

Most Trojans are malicious, but some are used in ethical hacking or penetration testing environments for training purposes.

Can Trojans be hidden in images or videos?

Yes. Through steganography or exploited vulnerabilities, Trojans can be embedded in seemingly harmless media files.

What industries are most targeted by Trojans?

Finance, healthcare, government, education, and remote-working sectors are top targets due to valuable or sensitive data.

What tools can defend against Trojans?

Effective defenses include firewalls, EDR solutions, zero-trust networks, DNS filtering, and ongoing user awareness training.