What is a Rootkit in Computer Terms? And Definition

A rootkit is a malicious software that allows an unauthorized user to have privileged access to a computer and to restricted areas of its software. A rootkit may contain a number of malicious tools such as keyloggers, banking credential stealers, password stealers, antivirus disablers, and bots for DDoS attacks. This software remain hidden in the computer and allow the attacker remote access to the computer.

The term rootkit is derived from the combination of two words – “root” and “kit”. “Root” refers to the administrator account in Unix and Linux operating systems, which is an all-powerful account with full privileges and unrestricted access. It is equivalent to the administrator account in Windows systems. The term “kit” refers to the programs that allow a threat actor to obtain unauthorized root/admin-level access to the computer and restricted areas. The rootkit enables the threat actor to perform all these actions surreptitiously without the user’s consent or knowledge.

What is Rootkit?

A rootkit is basically a type of malware which is designed to infect a target PC and allow the attacker to install a set of tools that grant the attacker remote access to the computer.

The malware is also designed to be hidden deep within the operating system. And it is designed to dodge any detection system that an antivirus program offers you. A rootkit program also contains a number of malicious tools, such as a keystroke logger, a password stealer, a module for stealing credit card or online banking information. As well as it can also include a bot for DDoS attacks or functionality that can disable security software.

Basically, rootkits act as a backdoor and give the attacker the ability to connect remotely to your computer. So the attacker can remove or install specific components. Some examples of Windows-based rootkits in active use today include TDSS, ZeroAccess, Alureon, and  Necurs.

Rootkit Variants

Two of the main types of rootkits are user mode rootkits and kernel mode rootkits. User mode rootkits are designed to run in the same part of the computer operating system as applications.

They usually execute their malicious behavior by hijacking application processes running on the machine. Or by simply overwriting the memory that an application uses.

On the other hand, the kernel mode rootkits are designed to run at the lowest level of the PC’s operating system. And this gives the attacker the most powerful set of privileges on the computer.

After the installation of the kernel mode rootkit the attacker would have complete control of the compromised computer. Also, the attacker can take any account that he or she wants to. Kernal mode rootkits are more complicated than the user mode rootkits. Also, they are less common. Also, kernel mode rootkits are hard to detect and remove.

Apart from these two, there are a few other common rootkit variants that are also available. Such as the bootkits, which is designed to modify the computer’s boot loader, the low level software that runs before the operating system loads.

Also, in recent years, mobile rootkits also have become a pretty common thing. They are emerged to attack smartphones. Especially the android devices. These rootkits often get installed on an Android device while installing an app from a third party source.

Method of Infection

Rootkits get installed on your computer through various methods. However, the most common infection vector is through the use of a vulnerability in the operating system or an application running on the computer.

The attackers mainly target known and unknown vulnerabilities in the operating system. After that, they use an exploit code to get the privilege position on the target machine. After that, they can install the rootkit and setup components that allow remote access to the computer.

The exploit code for a specific vulnerability may be hosted on a legitimate Web site that has been compromised. Another infection vector is via infected USB drives. Attackers may leave USB Drives with rootkits hidden on them in places where they are likely to be found and picked up by the victims. Such as buildings, coffee shops, conference centers. And the attacker gets access.

How to remove Rootkit?

Finally, the question is how to remove Rootkit? Detecting the presence of a rootkit on a computer can be a tough task. This kind of malware is designed not to be detected. And it must stay in the background doing its business. However, there are quite a lot of tools designed out there that can actually look for known and unknown types of rootkits through various methods.

Some of these methods include signatures or a behavioral approach that tries to detect a rootkit by looking for known behavior patterns. Removing a rootkit is a complex process and typically requires the use of specialized tools.