A Remote Access Trojan gives someone else complete control of your computer

A Remote Access Trojan (RAT) is malicious software that lets an attacker control your computer from somewhere else, just as if they were sitting at your keyboard. Once installed, a RAT lets the attacker see your screen, move your mouse, type commands, access your files, turn on your camera or microphone, and run programs — all without your knowledge or permission.

The word "Trojan" comes from the method: the software hides inside something that looks legitimate. You might download what appears to be a game, a utility, a document, or an update. Once you run it, the RAT installs itself and opens a hidden connection back to the attacker's computer. From that point forward, the attacker has a backdoor into your system.

RATs are different from other malware because they are designed for ongoing, interactive control rather than a single action like stealing passwords or displaying ads. An attacker using a RAT can watch what you do in real time, wait for you to enter sensitive information, or use your computer to attack other systems.

Key Takeaways

  • A Remote Access Trojan installs hidden software that lets an attacker control your computer remotely, seeing your screen and accessing your files without your knowledge.
  • RATs spread by disguising themselves as legitimate software, games, documents, or updates that you download and run yourself.
  • Once active, a RAT creates a persistent backdoor connection, meaning the attacker can return to your computer at any time.
  • RATs are often used for theft of financial information, extortion, corporate espionage, or to turn your computer into part of a botnet that attacks other systems.

How a Remote Access Trojan gets onto your computer

RATs spread through social engineering — tricking you into downloading and running them. Common delivery methods include email attachments that claim to be invoices, resumes, or urgent documents; fake software installers for popular programs; cracked or pirated versions of paid software; malicious links in messages that claim to show you something interesting; and compromised websites that automatically download files to your computer.

Some RATs also spread through security holes in software you already have. If your operating system, browser, or applications have unpatched vulnerabilities, an attacker can exploit those holes to install a RAT without you taking any action at all. This is why keeping your software updated matters.

Once the RAT runs, it typically installs itself in a hidden location on your hard drive and configures itself to start automatically when you restart your computer. It then connects to a server controlled by the attacker, establishing a two-way communication channel. From that moment on, the attacker can issue commands to your computer whenever they want.

What an attacker can do with a Remote Access Trojan

The capabilities of a RAT depend on how it was written and what permissions it has, but the most dangerous ones can do nearly anything your user account can do. An attacker can view everything on your screen, including passwords you type, banking information, private messages, and documents. They can access your files, copy them, delete them, or modify them. They can download additional malware onto your computer or use your computer to send spam or launch attacks against other systems.

RATs are often used for financial theft — an attacker watches you log into your bank account and transfers money out. They are used for extortion, where the attacker threatens to release private photos or information unless you pay. They are used for corporate espionage, where a competitor or foreign government steals trade secrets or intellectual property. They are also used to turn your computer into a botnet node, meaning your computer becomes part of a network of infected machines used to attack websites or send spam.

Some RATs include additional features like keystroke logging (recording every key you press), screen capture (taking screenshots at intervals), webcam and microphone access, and the ability to modify your browser settings or inject ads into websites you visit.

Signs your computer might have a Remote Access Trojan

A well-designed RAT tries to hide itself, so you may have no warning signs at all. However, some indicators suggest your computer might be compromised. Your computer might run slowly or freeze frequently, even when you are not using demanding programs. Your internet connection might be unusually slow or your data usage might spike, because the RAT is sending information to the attacker's server. Your mouse or keyboard might move or type on their own, or programs might open and close without you touching anything.

You might notice your antivirus software has been disabled, or security alerts appearing and then disappearing. Your webcam light might turn on when you are not using video calls. Files might go missing or change without your action. Your friends might receive messages from you that you did not send. Your computer might restart on its own or crash frequently.

However, the absence of these signs does not mean you are safe. Many RATs are designed to be invisible. The only reliable way to know whether your computer is infected is to run a full scan with reputable antivirus or anti-malware software.

The difference between a Remote Access Trojan and other malware

RATs are often confused with other types of malware, but they work differently. A virus replicates itself and spreads to other files or computers. A worm spreads on its own without needing you to run anything. Spyware watches what you do and reports back, but does not necessarily give an attacker direct control. A keylogger records your keystrokes but does not let the attacker interact with your system in real time.

A RAT combines elements of these — it hides like a Trojan, it watches like spyware, and it gives the attacker direct, interactive control like a backdoor. This makes RATs more dangerous than most other malware, because an attacker can adapt their actions based on what they see happening on your computer right now, rather than following a pre-programmed script.

How to reduce your risk of infection

The most important step is to be cautious about what you download and run. Do not download software from unfamiliar websites or from links in unsolicited emails or messages. Download programs only from official websites or trusted app stores. Be suspicious of email attachments, especially from people you do not know or from unexpected messages claiming to be from companies you use. If someone sends you a file you were not expecting, contact them through a separate channel to confirm they actually sent it.

Keep your operating system, browser, and all installed software up to date. Security updates patch the holes that attackers use to install RATs without your knowledge. Enable automatic updates if your system offers that option. Use reputable antivirus or anti-malware software and keep its definitions current. Run full system scans regularly, not just quick scans.

Use strong, unique passwords for important accounts like email and banking, and consider using a password manager to keep track of them. Enable two-factor authentication wherever it is offered, so that even if an attacker steals your password, they cannot access your account without a second form of verification. Be cautious about what you share online, because attackers often use personal information to make social engineering attempts more convincing.

What to do if you think you have a Remote Access Trojan

If you suspect your computer is infected, disconnect it from the internet immediately. This stops the RAT from communicating with the attacker's server and prevents it from sending your data or receiving new commands. Do not assume the infection is limited to one user account — RATs often install themselves in locations that affect the entire computer.

Run a full system scan with reputable antivirus software in Safe Mode, which loads only essential system files and makes it harder for malware to hide or interfere with the scan. If the scan finds and removes a RAT, restart your computer in normal mode and run the scan again to make sure the infection is gone. If your antivirus software cannot remove the infection, or if you are not confident the computer is clean, consider taking it to a professional or backing up your important files and reinstalling your operating system from scratch.

If the RAT was used to steal financial information, contact your bank and credit card companies immediately. If passwords were compromised, change them from a different, clean computer. Monitor your accounts for unauthorized activity. Consider placing a fraud alert or credit freeze with the credit bureaus if you believe your identity information was stolen.

Frequently Asked Questions

Can a Remote Access Trojan work on a Mac or Linux computer?

Yes. While most RATs target Windows computers because Windows is the most common operating system, RATs exist for macOS and Linux as well. No operating system is immune. The same prevention methods apply: keep your system updated, be cautious about what you download, and use antivirus software.

Can a Remote Access Trojan see me through my webcam?

Yes, if the RAT includes that capability and your camera is connected. Some RATs are specifically designed to access webcams and microphones. This is why some security experts recommend covering your webcam with tape or a physical cover and muting your microphone when you are not using them.

If I disconnect from the internet, will the Remote Access Trojan stop working?

The RAT itself will still be on your computer, but it will not be able to communicate with the attacker or receive new commands. However, it will try to reconnect as soon as your internet comes back on. Disconnecting buys you time to scan and remove the infection, but it is not a permanent solution.

Can antivirus software detect a Remote Access Trojan?

Good antivirus software can detect many RATs, especially older or well-known ones. However, new or heavily customized RATs may not be in the antivirus database yet, so they might not be caught immediately. This is why layered protection — keeping software updated, being cautious about downloads, and running regular scans — is more effective than relying on antivirus alone.

Is a Remote Access Trojan the same as remote desktop software?

No. Remote desktop software like TeamViewer or Windows Remote Desktop is legitimate and requires your permission to install and use. A RAT is malicious software installed without your knowledge or consent. The difference is consent and transparency — legitimate remote access tools tell you they are running and let you control who can access your computer.