What is a Remote Access Trojan or RAT?

A Remote Access Trojan or RAT is a type of malware that infects a remote computer and allows remote access to the computer to the attacker. As a result, the attacker can exploit the remote access for malicious purposes. A Remote Access Trojan (RAT) is usually installed on a computer secretly without the user’s knowledge and hides its operation from the security software installed on the computer.

Usually, these RATs infect a computer when a user clicks on a malicious link, downloads untrusted software, or uses Peer-to-Peer File Sharing software like BitTorrent. A RAT often disguises itself as a legitimate program or file. After infecting a computer, a file or stub is opened on the victim’s computer, and the attacker gains control of the computer. Usually, the file itself may not create much suspicion. If a user clicks on it, it may show an error message indicating the file could not be opened.

How does a Remote Access Trojan (RAT) work?

RAT is a malware program. So, like other malware programs, it infects a computer using deception. It usually disguises itself as some software that is desirable and harmless and convinces an innocent user to install it. (What is social engineering?)

A RAT may come as an email attachment. It can also get installed on a computer along with some other useful-looking malicious software. For example, it may disguise itself as an attractive video game from an untrusted source or a rogue anti-malware program that fraudulently indicates that the computer is already infected by malware. It thus convinces the user to install it. A Remote Access Trojan (RAT) can also infect a computer when the user clicks on a malicious link or visits a malicious website.

After infecting the computer, the RAT connects back to the attacker remotely. And, as the malware program has remote administrative capability, it gives complete unauthorized access to the computer to the attacker.

The attacker can now control the computer remotely and exploit the remote access for malicious purposes.

What does a Remote Access Trojan (RAT) do?

A Remote Access Trojan (RAT) gets administrative privileges on the infected computer. So, it can perform many malicious activities by exploiting administrative privileges. Some of them are mentioned below:

• As a RAT gets administrative privileges on the infected computer, it can exploit that to control the microphone or webcam of the infected computer. It can record sound and videos and spy on the victim. It can even capture screens of the computer for malicious purposes.
• It can install keyloggers and start logging keystrokes on the computer (What is a keylogger and how to prevent it?). Using keyloggers attackers can steal sensitive data like passwords and credit card numbers of the user. In fact, it is always a piece of good advice to use the virtual keyboard on a banking website and not to type any password using the computer keyboard.
• A Remote Access Trojan collects sensitive data from the infected computer and sends the data to the attackers. It can upload, download, or destroy sensitive files or other data.
• Many a time,  Remote Access Trojans infect computers and exploit the computational resources of the infected computer to perform illegal actions like DDoS attacks.
• A RAT can silently install even more malware on the infected computer and perform illegal activities. Sometimes, it changes the browser settings for malicious purposes. (What is browser hijacking and how to prevent it?)
• As a Remote Access Trojan (RAT) gets administrative privileges on the infected computer, the attacker can do anything that the admin user of the computer can. The attacker can shut down or restart the computer at his own will to facilitate their malicious activities. The attacker can block or control the mouse and keyboards, control the task manager of the computer, format the drive, or even destroy the hardware of the computer, for example, by increasing the clock rate of the system.

One such example of a RAT is Back Orifice. It targeted Microsoft Windows computers and …