What is a Remote Access Trojan (RAT)? A cybersecurity guide

Think of all the things you can do with your computer or smartphone. You can take and store photos of yourself and your family, speak to people all over the world on video calls, organize your finances, purchase goods and services, trace your exact location, and so much more.

But what if someone else had access to all that information of yours? Imagine the scale of the chaos they could cause to your day-to-day life, your loved ones, and your financial well-being.

This is the scale of the impact that a Remote Access Trojan - also known as a RAT virus - can have by infecting a device. They’ve been around for a long time but are still having success in seizing control of devices all over the world, so it remains critical that every online user takes steps to protect themselves from this ongoing threat.

In this guide, we’ll explore how a Remote Access Trojan works, the types of criminal activity that they’re used for, and what you can do to prevent remote hacking and RAT malware from affecting your devices and data.

What is a Remote Access Trojan and how does it work?

Trojans are one of the most well-known types of computer malware. They’re named after the famous Trojan Horse of Greek mythology, where soldiers besieging the city of Troy hid themselves in a large wooden horse that was presented to the city as a gift. Once the Trojans brought the horse inside the city gates, the Greek soldiers crept out of the horse under cover of darkness and opened the gates, allowing the rest of the Greek army inside to destroy the city.

Trojan viruses follow the same principle: pretending to be something else - normally a legitimate file, link, attachment, or application that a user might want or need - to give hackers and cybercriminals a level of access that they would not normally (or legally) be able to obtain. More specifically, a Remote Access Trojan is designed to give a hacker full access to a device and all of the information within it.

So how does a Remote Access Trojan work in practice? Once a RAT has been downloaded into a computer, it connects to an open TCP port, so that it can create an online connection to the hacker’s machine. Through this connection, the hacker can take full control of the device, from adding and removing applications and data to obtaining sensitive data and credentials that allow them to commit crimes such as wire fraud and identity theft.

RATs are slightly different from keyloggers, which is a type of malware that tracks every keystroke a user makes in order to seize passwords and other typed information. However, it isn’t uncommon for keylogging capabilities to be rolled into RATs alongside other tracking functions.

What are the main examples of a RAT trojan?

Remote Access Trojans are not especially new threats, but they have diversified over the years. There are several different major types of RAT malware out there, targeting users through different tactics and different platforms. These include:

Mirage (state-level)

This RAT is believed to have been developed by a hacking group supported by the Chinese government, with the aim of interfering with government and military organizations in other countries.

Saefko (browsing)

A RAT that can monitor the browsing activity and history of users, with a view to stealing information around cryptocurrency transactions.

PoisonIvy (Word and PDF phishing)

Spear phishing emails containing malicious attachments, regularly target businesses and governmental bodies.

Blackshades (social media)

A self-expanding type of RAT attack that can send malicious links through social media accounts of infected devices, therefore impacting more and more people over time.

RomCom (app impersonation)

A RAT attack that started in 2022 by pretending to be a range of different software applications, including PDF Reader Pro and SolarWinds Network Performance Monitor.

Cloud9 (Google Chrome)

A new RAT virus that can steal credentials for online accounts through the Chrome browser and also use it to stage distributed denial of service (DDoS) attacks.

Why is the RAT virus so dangerous?

RAT malware can be considered particularly dangerous because they can give hackers total access to everything on a device and then use that access to wreak havoc in several different ways. And while they are often targeted at larger organizations because of the potential financial or political rewards on offer, anyone could be a victim of RAT malware with catastrophic consequences.

Many RAT computer hackers have been known to:

Stage DDoS attacks

When RAT malware infects large numbers of devices, they can all be coordinated to overwhelm a target server with Internet traffic, launching a DDoS attack and causing it to shut down.

Steal identities

Device access means hackers can pick up passwords and account information, the content of emails and messages, as well as personal photos and other highly sensitive data. This information is more than enough for them to conduct identity theft, steal money from bank accounts, or obtain goods and credit with the user’s data and personal characteristics.

Hold users to ransom

Connected to the previous point, hackers can lock users out of being able to access their accounts and data and blackmail them into paying a ransom in return for restoring access.

Remove data

Hackers can also use their access to remove or delete any type of data they wish to. For the user, this would mean that any data created after their most recent backup would be permanently lost.

Use the device for illegal data storage

Many hackers are involved in other illegal activities and may use hacked devices to store information that they wish to keep out of the prying eyes of the authorities.

Use the device for crypto mining

Hacked devices can also be used for cryptojacking, where hackers mine cryptocurrencies such as Bitcoin. This is because mining consumes large quantities of energy and computing power, so using somebody else’s device to do it can make things easier and cheaper for the hacker - especially if spreading the load across many different devices simultaneously.

How can RAT malware be detected?

As with most viruses, an RAT virus has certain characteristics that it generates within a device that it infects. Typical symptoms of a Remote Access Trojan include (and are not necessarily limited to):

Unexpected website redirects

An RAT trojan will often cause browsers to constantly redirect users to different web pages over and over, or to suddenly find it difficult to load up web pages.

Unexplained files

RATs can often install files and applications within a device without the user being aware that they exist there. Any applications or files that a user can’t remember downloading or installing can often be a pointer towards malicious activity.

Irregular webcam activity

It has been known for the RAT trojan to turn webcams on so that the hacker can track the user both audibly and visually. Users should be wary of irregular webcam activity such as if their webcam ‘on’ light comes on unexpectedly, especially if their usual video collaboration applications aren’t being used at the time.

Slow computer/processor performance

Any RATs running on a device will consume significant amounts of processor capacity and will therefore slow down everything else. If a device starts running unusually slowly (or even becomes hot and noisy in its operation), then RAT malware may be the reason why.

It’s important to remember, however, that no two attacks are the same, and so an infected device may show all or some of these symptoms or even none of them. For this reason, whether you think your device has been infected by a RAT trojan or not, ongoing cybersecurity hygiene is essential.

What should you do if you’re hit by a RAT virus infection?

If your device has been infected with a Remote Access Trojan, then you should proceed with caution when it comes to its removal. We recommend following this process:

Install anti-virus software

Ensure you have good-quality anti-virus software such as Kaspersky Anti-Virus installed and ready to go. If you already have one installed, make sure it has been updated to the latest available version.

Turn off the Internet connection

Breaking the connection between the device and the Internet in the first instance prevents any further communication between the RAT virus and the cybercriminal’s server so that no further data can be obtained.

Restart in ‘Safe Mode’

Restart your computer and press the F8 key during startup, so that the machine is rebooted in ‘Safe Mode’.

Run a full anti-virus scan

Use your chosen anti-virus platform to conduct a full system scan, which should detect the RAT virus (along with any other malware that may be on the device). Then follow instructions to delete/quarantine the virus accordingly.

Change passwords and other credentials

Update passwords for all your online accounts and store them safely, so that the existing credentials that may have been breached are no longer usable.

Monitor your bank accounts closely

Keep a keen eye on your accounts and bank statements for any unusual activity and notify your banking providers if you think that your funds may be at risk.

What can you do to prevent the RAT virus from infecting your devices?

Of course, the best possible way to prevent a RAT trojan from having any impact on your device or data is to minimize the risk of an infection in the first place. This not only requires good use of RAT cybersecurity technology but also the continuous application of security best practices. As part of this, we recommend the following:

• Never open links and attachments you don’t trust: This may sound simple, but it’s surprising just how many people still fall foul of unknown attachments and links and invite infection from a RAT virus or other malware. To prevent the risk of phishing scams, only open links and attachments from sources that are verifiably genuine.
  
• Only download software from legitimate, trusted sites: like the previous point, software applications available on relatively unknown sites aren’t always what they say they are. The best way to avoid the risk of unwittingly downloading the RAT malware is to stick to reputable app stores and industry-recognized app download sites.
  
• Cover your webcam when not using it: if a webcam lens is left uncovered and a RAT virus infects a device, it would potentially allow a hacker to visually spy on a user 24 hours a day. That’s why it’s good practice to keep a webcam covered at any time when it isn’t needed.
  
• Utilize a Virtual Private Network (VPN): many hackers using the RAT trojan will want to track your activity online, and using a good VPN will prevent them from being able to do this. Kaspersky VPN Secure Connection, for example, will secure your IP address even on unsecured Wi-Fi hotspots, and prevent data leaks.
  
• Update your operating system regularly: operating system updates routinely contain the latest security patches and enhancements and therefore provide stronger protection against new and emerging threats. For this reason, you should make sure you update your OS as often as you can. If you currently run Windows 10, you should look at upgrading to Windows 11 as soon as possible, as Microsoft is ending official W10 support in October 2025.
  
• Usemulti-factor authentication wherever possible: many banking platforms and other online services now offer multi-factor authentication, where (for example) you may be asked to enter a code, you receive by text message to confirm your identity. This adds an extra layer of protection against cyber hackers, who may be able to gain your password through RAT malware but would not be able to pass the MFA checks. Therefore, you should make use of MFA functionality in all the places where it’s available.
  
• Install and run anti-virus software: a good anti-virus solution should be standard practice across all your devices but can be particularly useful in detecting and shutting down a RAT trojan quickly. Kaspersky Premium offers advanced protection from viruses and real-time data leak monitoring, which help ensure that the impact of any RAT virus is kept to an absolute minimum.

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