Beginner’s Guide to Remote Access Trojans (RAT)

Something’s not right…

Your webcam light flickers, files disappear, or your mouse moves on its own. Maybe it’s a glitch but it could also be a remote access trojan (RAT). Hidden in the background and allowing someone to control your device without you even knowing it!

But how do they get in? What makes them so dangerous? And most importantly, how can you spot and remove them before they cause damage?

If you’re serious about cyber security — whether defending yourself or testing defenses ethically — understanding RATs is essential. So let’s break them down.

Sidenote: Want to learn how to use the tools in this guide (and more) to become an Ethical Hacker or simply learn to protect your systems better? Then check out my complete Ethical Hacking course!

You'll learn by using real techniques used by black hat hackers and then learn how to defend against them.

I guarantee that this is the most comprehensive and up to date Ethical Hacking course that you can find. You will learn and master the most modern ethical hacking tools and best practices to the point that you're able to get hired!

With that out of the way, let’s get into this guide…

What are Remote Access Trojans

Named after the Trojan horse from Greek mythology, A remote access trojan (RAT) is a type of trojan malware - a program that seems harmless but secretly carries a hidden payload.

However, instead of adding viruses or ransomware that locks up files and demands money, RATs are usually quiet. In fact, you might not even know they are there until a program starts behaving slightly strange or your internet slows down.

Why do they do this?

Because it’s much better for the hacker in the long run. You see, RATs are used to give someone else full remote control access to your system as if they were sitting in front of your screen. (Hence the name).

This means that once a RAT is in, the attacker can do almost anything:

Browse files
Install programs
Log your keystrokes
Take over your webcam
Or even move your mouse in real time

Even worse?

Without the right protections, your computer could be hijacked and used in cyberattacks, whether against corporations, governments, or even other individuals.

That’s what happened recently with Twitter and their DDoS attack. Thousands of people’s computers were already hacked and then used as a botnet without them even knowing.

Heck, they probably still don’t know they’re infected!

The question of course, is how do RATs get onto a device in the first place? Well, they’re sneaky…

How Remote Access Trojans get onto your devices

Most RATs don’t force their way in. Instead, they trick you into letting them in. That’s what makes them so effective.

Attackers have several ways to spread RATs:

Phishing emails. Fake emails disguised as urgent messages, often containing malicious attachments or links. One click, and you’ve installed a RAT without realizing it. Most people are getting better at recognizing this, which is why these other methods have started to increase
Fake software downloads. Ever downloaded a “free” version of software from an unofficial site? Some RATs are bundled with cracked software or disguised as security updates
Malicious ads (malvertising). Even legitimate websites can unknowingly serve ads containing hidden RAT downloads. One bad click, and the malware installs silently.
USB drops. Attackers sometimes leave infected USB drives and sockets in public places, such as airport chargers or hospitals - hoping someone will plug them in

Sidenote: Learning cybersecurity from an ethical hacker’s perspective?

RATs are often used in red team exercises to simulate real-world breaches and test an organization’s ability to detect and respond to stealthy threats. Understanding how they work from both sides is a huge advantage.

How Remote Access Trojans work

Once a RAT gets onto your device, it doesn’t just sit there like a virus waiting to spread. It immediately starts setting up shop — disguising itself, hiding its tracks, and quietly opening a connection to its controller.

The first thing it does is install itself silently, often renaming the file to look like something harmless, like a system update or background service
From there, it usually disables your antivirus tools, adds scheduled tasks to restart itself on boot, and buries parts of itself in places like AppData or the Windows registry.
Then comes the really dangerous part: the command-and-control connection (C2). This is the remote link that lets the attacker send commands to your system. Think of it like a secret tunnel between your device and the hacker’s machine. Through this tunnel, they can browse your files, log your keystrokes, take screenshots, or even turn on your webcam and watch in real time.

Some RATs also use encryption or mimic trusted system processes to avoid detection — so even if you're watching your system’s activity, nothing stands out at first glance. That’s why they can stay hidden for days, weeks, or even months.

So how do we find them?

How to detect Remote Access Trojans

As I said earlier, most RATs are designed to stay hidden. They don’t announce themselves with pop-ups or obvious signs of infection. But even the most stealthy RATs leave behind clues.

Here’s what to watch for:

Unusual system behavior

If your device starts acting strangely without explanation, it could be a sign of a RAT infection. Common red flags include:

Your mouse moves on its own or clicks things without your input
The webcam light turns on when you’re not using it
Files appear, disappear, or move without reason
Programs suddenly open or close by themselves

These aren’t just glitches. If you’re noticing multiple strange behaviors at once, something else might be in control of your system.

Increased network activity

Even if a RAT stays hidden, it still needs to communicate with the attacker’s remote server. That means unusual network traffic, especially when you’re not actively using the internet.

To check:

Open Task Manager (Windows) or Activity Monitor (Mac) and look for programs using high amounts of network data
Use netstat or Wireshark to monitor outgoing connections—if your device is connecting to unknown IPs, that’s a red flag
Look for spikes in upload activity when you're not actively sending files

If your computer is constantly “phoning home” to a strange server, a RAT could be the reason.

Suspicious background processes

Although RATs often disguise themselves as normal system files, they still need to run in the background.

You can check for hidden processes using:

Task Manager (Windows) or Activity Monitor (Mac) – Look for unfamiliar or suspiciously named processes using high CPU or memory
Autoruns (Windows) – This tool shows everything that runs on startup, including hidden malware
Process Explorer – A more advanced alternative to Task Manager that can show which processes are making network connections

If you see a process running that you don’t recognize and can’t close, that’s a bad sign.

Antivirus and security tool alerts

Some RATs are advanced enough to disable security tools, but most leave traces that a good antivirus can detect. Running a full system scan with a reputable antivirus or anti-malware tool (like Malwarebytes or Windows Defender) can help identify and remove infections.

Important: If your security software suddenly stops working, refuses to update, or won’t open, that could mean a RAT is actively trying to prevent detection!

How to remove Remote Access Trojans from your device

If you suspect a remote access trojan (RAT) is hiding on your system, you need to act fast.

Step #1. Disconnect from the internet

The first thing you should do is cut off the attacker's access by disconnecting from the internet. This prevents them from controlling your system in real time or exfiltrating data while you work on removing the RAT:

Unplug your ethernet cable or disable Wi-Fi from your settings
If possible, disconnect your router to stop all outbound traffic while investigating
Make sure your device isn’t connected to your mobile device as a hotspot

This won’t remove the RAT, but it will prevent further damage while you clean up your system.

Step #2. Boot your device into safe mode

Many RATs run as background processes and restart automatically when your system boots up. Running your computer in Safe Mode prevents unnecessary programs from launching, making it easier to remove malware.

Windows: Restart and press F8 or Shift + Restart → Select Safe Mode with Networking
Mac: Restart and hold Shift until you see the Apple logo

Once in Safe Mode, the RAT’s control mechanisms may be disabled, giving you a better chance at removal.

Step #3. Scan with a trusted antivirus or anti-malware tool

A good anti-malware tool can detect and remove most RATs, so use one of the following:

Windows Defender (built into Windows 10/11) – Run a full system scan
Malwarebytes – Effective at detecting hidden trojans and RATs
Kaspersky, Bitdefender, or Norton – Strong real-time protection against advanced threats

Make sure to run a full scan and remove any threats detected.

Important: If your antivirus is disabled or won’t run, that could be a sign that the RAT is actively trying to protect itself. In that case, try running the scan in Safe Mode or using a bootable rescue disk (like Kaspersky Rescue Disk).

Step #4. Clean up and lock your system down

Removing a RAT is only part of the job. Once it’s out, you still need to clean up any damage, lock down your system, and prevent the attacker from sneaking back in.

Don’t skip this step! RATs are built to stay hidden, so it’s common for them to leave behind secret access points so they can be added back again later.

Reset your firewall and system permissions

Start by restoring your firewall and security settings to their defaults. RATs often create custom rules to let traffic in or out without you noticing, so go ahead and check:

In Windows, open the Defender Firewall settings and click “Restore defaults”
While you’re at it, check your port forwarding rules on your router. If you see anything unfamiliar — especially open ports you didn’t configure — block or delete them

Change your passwords (yes, all of them)

Even if the RAT didn’t seem to target your accounts, assume it captured everything you typed. That includes email logins, banking credentials, work accounts — basically anything you've entered with a keyboard.

Start with your most critical accounts:

Email
Cloud storage
Banking and payment apps
Work-related tools

Use a password manager to generate unique, strong passwords for each one. If your services offer it, log out of all sessions to kick out any unauthorized users who may still be connected.

Review login activity and account changes

Many services log where and when you last signed in. Now’s the time to check for logins you don’t recognize:

For Google: Google Security Checkup
For Microsoft: Microsoft Account Security

If you see any unfamiliar activity, change your password again and make sure to enable two-factor authentication while you’re at it. This will help prevent future hacks. (More on these later).

Scan everything else on your network

RATs don’t always stay on the first device they infect. If your PC was compromised, other connected devices might be at risk too:

Run a full malware scan on laptops, phones, tablets, and even smart devices
Log into your router and check the list of connected devices. Anything unfamiliar? Block it or investigate
If you notice DNS settings or network configurations that don’t look right, reset your router to factory settings and set it up from scratch

Hunt for hidden backdoors

Some RATs don’t give up easily. They leave behind hidden user accounts, scheduled tasks, or registry edits designed to reopen access.

Here's how to flush them out.

Open Command Prompt in Windows and type:

net user

If you see any accounts you didn’t create, investigate immediately. Use Autoruns (Windows) or Activity Monitor (Mac) to review programs that launch at startup.

Check for suspicious scheduled tasks

Head across to C:\Windows\System32\Tasks. This is where Windows stores instructions for things that run automatically such as software updates, background services, or security checks.

The reason you need to check this is because RATs can abuse it by setting up hidden tasks that restart the malware every time you reboot, or run it silently on a schedule so you don’t notice anything wrong:

You’ll want to open Task Scheduler (taskschd.msc) to get a clearer view
Then expand the folders on the left and go through them slowly
Look for tasks with weird or generic names like Updater, SystemCheck, or random-looking strings
Pay special attention to any task that’s running something from unusual locations, like AppData, Temp, or an external drive path

To see what a task is actually doing, right-click it and open Properties, then check the Actions tab. That will show you the exact command it's running.

If you don’t recognize it, Google the filename or path. And if something feels off, disable the task instead of deleting it — just in case it turns out to be something critical.

Step #5. Watch for lingering threats and notify others

Even after you've locked everything down, it’s a good idea to stay alert for signs of trouble over the next few days or weeks.

Monitor your network for anything sketchy

RATs often communicate in small bursts, so it’s worth watching for anything unusual.

Use tools like GlassWire or Wireshark to monitor outgoing connections
If you see your system talking to unknown servers, block the IP addresses at the router level
Still seeing strange traffic? A full router reset and firmware update might be your best bet

Let people know, if needed

If the RAT had access to your email or messaging accounts, it may have sent phishing messages or spam from your name. Take a minute to notify any affected contacts — especially if you see signs that someone responded.

And if this happened on a work device, report it to your IT team immediately. They need to know what data might’ve been compromised, and they’ll likely want to scan connected systems for follow-up.

Stay alert for fraud and phishing attempts

Even after the RAT is gone, attackers may still try to use any info they grabbed. That could include:

Fake calls pretending to be from your bank
Phishing emails using real details they scraped from your files
Unauthorized purchases or account changes

If anything looks off just trust your gut. Change passwords again, lock down sensitive accounts, and consider placing a fraud alert with your financial institutions if needed.

It’s easier to remember a new password than it is to get money back that was stolen…

Step #6. If all else fails, consider a full system reinstall

If the RAT is deeply embedded or keeps coming back, the most foolproof way to remove it is wiping your system and reinstalling your OS:

Windows: Use the “Reset this PC” option to perform a clean reinstall
Mac: Boot into macOS Recovery (Command + R) and reinstall macOS

While this is a last resort, it guarantees that no remnants of the RAT remain.

It does suck to have to reinstall everything again, but it’s worth it for the best peace of mind. You can even use it as a mental rest on your cyber security habits to make sure it doesn’t happen again in the future.

Which leads us to our final section.

How to prevent future RAT infections

Now that the RAT is gone, how do you make sure it never happens again?

Don’t download files from unknown sources. This includes cracked software, suspicious email attachments, and unofficial “security updates.” Heck, even double check trusted sources just in case!
Use strong antivirus software. Keep it updated and enable real-time protection
Enable firewall protection. A strong firewall can block RATs from communicating with their command-and-control server. Most antivirus will have this included so it’s another reason to get it if you haven’t already
Use multi-factor authentication (MFA). If your passwords were stolen, MFA can prevent attackers from accessing your accounts, as they need to verify a code on your mobile device for it to work. Google offers MFA for free on any mobile device
Monitor network activity. Install and use tools like GlassWire or Wireshark to detect suspicious traffic. This can help you stay on track if a new install happens or if the RAT reappears
Regularly update your software. Many RATs exploit known vulnerabilities. Keeping your system up to date closes security holes attackers rely on

Is your system safe?

So as you can see, RATs are dangerous because of how long they can stay hidden while giving attackers full control of your device. But now you know how they work, how they spread, and how to spot them.

So here’s your next move: Go ahead and take 10 minutes to check your system. Look for strange behavior, unknown processes, or suspicious tasks. Run through the steps in this guide — even if it’s just to be sure.

Because the scariest RAT infections are the ones you never knew were there!

P.S.

Remember - If you want to learn how to use the tools in this guide (and more) to become an Ethical Hacker or simply learn to protect your systems better? Then check out my course!

You'll learn by using real techniques used by black hat hackers and then learn how to defend against them.

I guarantee that this is the most comprehensive and up to date Ethical Hacking course that you can find. You will learn and master the most modern ethical hacking tools and best practices to the point that you're able to get hired!

Better still?

If you join ZTM as a member, then you’ll get access to each of my cyber security courses, as well as access to our private Discord server.

Here you can chat to me, other students, and working cybersecurity professionals and get help with any questions you might have 24/7.