What a Remote Access Trojan Does

A remote access trojan (RAT) is malware that gives someone else complete control over your computer while you are using it. Unlike ransomware that locks your files or spyware that watches what you do, a RAT lets an attacker open programs, move your mouse, type on your keyboard, access your files, and change your settings — exactly as if they were sitting at your desk.

The attacker does not need to be near you. They connect to your computer over the internet from anywhere in the world. Once the RAT is installed, you might not notice anything unusual happening, which is why these trojans are particularly dangerous. The attacker can work slowly and quietly, stealing passwords, installing additional malware, or using your computer to attack other machines.

The word "trojan" comes from the method of delivery, not what the malware does. Like the wooden horse in the ancient story, a RAT arrives disguised as something else — a game, a software update, a document, or an email attachment. You run it thinking it is legitimate, and only then does it install the remote access capability.

Key Takeaways

  • A remote access trojan gives an attacker the ability to control your computer remotely, including opening files, installing programs, and viewing your screen.
  • RATs often arrive through email attachments, fake software downloads, or compromised websites, and may run silently without obvious signs of infection.
  • An attacker with RAT access can steal passwords, banking information, and personal files, or use your computer to send spam and attack other systems.
  • Protecting against RATs means keeping your operating system and software updated, using antivirus software, and being cautious about what you read and open.
  • If you suspect a RAT infection, disconnect from the internet when ready and run a full antivirus scan before using the computer for sensitive tasks.

How a Remote Access Trojan Gets Onto Your Computer

RATs arrive through the same channels as other malware, but they are often more carefully disguised because the attacker wants you to run them without suspicion. Common delivery methods include email attachments that look like invoices, resumes, or documents; fake software installers for popular programs; and compromised websites that try to read malware when you visit.

Some RATs come bundled with legitimate software you read from unofficial sources. A cracked version of a game or a free version of paid software might include the trojan alongside the program you thought you were getting. Others arrive through drive-by downloads, where visiting a malicious website automatically attempts to install the malware without any action on your part.

Attackers also use social engineering to trick you into running the RAT. They might send an email claiming to be from your bank, your employer, or a service you use, with an urgent reason to open an attachment or click a link. The more convincing the message, the more likely you are to lower your guard.

What an Attacker Can Do Once They Have Access

Once a RAT is installed and the attacker connects, they have nearly the same capabilities you do on your own computer. They can see your screen in real time, move your mouse, and type commands. This means they can open your email, browse your files, take screenshots, and watch you enter passwords.

An attacker with RAT access can steal sensitive information: banking passwords, credit card numbers, social security numbers, tax documents, or personal photos. They can install additional malware, including ransomware or spyware. They can modify files, delete evidence of their presence, or change your settings to make your computer more vulnerable to future attacks.

Your computer can also be used as a tool to harm others. Attackers sometimes use infected machines to send spam emails, launch attacks on other websites, or mine cryptocurrency without your knowledge. This happens in the background while you use your computer normally, and you might not realize it is happening until your internet bill spikes or your computer slows dramatically.

Signs That Your Computer Might Be Infected

A well-hidden RAT may show no obvious signs at all, which is why prevention is more important than detection. However, some infections do leave traces. Your computer might run noticeably slower, especially when you are not using any programs. Your internet connection might be unusually slow or your data usage might spike without explanation.

You might notice your mouse moving on its own, programs opening without you clicking them, or files being modified or deleted when you did not touch them. Your antivirus software might alert you to suspicious activity, or you might see unfamiliar programs in your list of installed software. Some RATs create a hidden user account on your computer, which you can check by opening Settings and looking at your user accounts.

Be especially alert if you notice unusual activity after opening a suspicious email attachment or downloading something from an unfamiliar source. The sooner you act, the less damage the attacker can do.

How to Protect Your Computer From Remote Access Trojans

The strongest defense is prevention. Keep your operating system and all software updated, because updates patch security holes that RATs exploit. Turn on automatic updates so you do not have to remember to do it manually. Use antivirus software from a reputable company and keep its virus definitions current.

Be cautious about what you read and where you read it from. Use official websites and app stores rather than third-party read sites. Do not open email attachments from people you do not know, and be skeptical of attachments from people you do know if the message seems unusual or urgent. Hover over links in emails to see where they actually point before clicking.

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 on accounts that offer it, which prevents an attacker from accessing your accounts even if they steal your password. Avoid using the same password across multiple sites.

What to Do If You Think Your Computer Is Infected

If you suspect a RAT infection, disconnect your computer from the internet when ready. Unplug the ethernet cable or turn off Wi-Fi. This stops the attacker from accessing your computer remotely and prevents your computer from being used to attack others.

Run a full antivirus scan using reputable antivirus software. If your regular antivirus does not detect anything, try a second opinion scanner like Malwarebytes, which specializes in detecting malware that standard antivirus software might miss. Restart your computer in Safe Mode with Networking before running the scan, which limits what malware can do while the scan runs.

If the scan finds and removes a RAT, change all your passwords from a different device (like a phone or tablet) before using the infected computer for sensitive tasks again. If you entered banking information or credit card numbers while the RAT was active, contact your bank and credit card companies to report the potential compromise. Consider placing a fraud alert with the credit bureaus.

The Difference Between RATs and Other Malware

A remote access trojan is different from spyware in that it gives real-time control rather than just monitoring. Spyware watches what you do and reports back; a RAT lets the attacker do things themselves. A RAT is different from ransomware in that it does not lock your files or demand payment — the attacker's goal is usually to steal information or use your computer as a tool, not to extort you.

Some infections combine multiple types of malware. A single piece of malware might include RAT functionality, spyware, and the ability to read and install ransomware. This is why a single infection can be so damaging and why removing it completely is important.

Frequently Asked Questions

Can a RAT see me through my webcam?

Yes, if your computer has a webcam and the RAT includes that capability, an attacker can access it. This is why some security experts recommend covering webcams with tape or a small sliding cover. Check your camera settings to see if any unfamiliar programs have permission to use your webcam.

Will my antivirus catch a RAT automatically?

Most reputable antivirus software will detect known RATs, but new or heavily modified versions might slip through. This is why keeping your antivirus updated and using additional tools like Malwarebytes is important. No security tool catches everything, which is why prevention through caution is your best defense.

If I disconnect from the internet, will the RAT be removed?

Disconnecting stops the attacker from accessing your computer, but it does not remove the malware. The RAT remains installed and will reconnect the next time your computer is online. You must run antivirus scans and remove the infection itself, not just cut off the attacker's access.

Can a RAT spread to other devices on my network?

Some RATs can spread to other computers and devices connected to your home network, though most focus on the single infected machine. If you suspect infection, disconnect the infected computer from your network and do not use it to access other devices until the infection is removed.

Is it safe to use my computer after removing a RAT?

After a successful removal and restart, your computer is generally safe to use. However, change all your passwords from a different device first, and monitor your accounts for suspicious activity. If the attacker had access for a long time, they may have stolen information that could be misused later.