What is a rootkit and how does it affect?

A rootkit is a malicious software package designed to allow unauthorized access to a computer or other software. Rootkits are difficult to detect and can hide their presence on an infected system. Hackers use this type of malware to remotely access your computer, manipulate it and steal data.

When a rootkit takes root on your system, it behaves like a zombie computer and the hacker can use remote access to exert absolute control over your device. This part of the rootkit definition is what gives them so much power.

What does a rootkit do?

Rootkits allow malicious code to hide on your device. When a rootkit attacks your computer, it authorizes remote administrator access to your operating system while avoiding detection.

What does a rootkit modify? Since the purpose of a rootkit is to gain privileged, administrator-level access to your computer’s system, a rootkit can perform the same modifications as an administrator. Below is a brief list of what a rootkit can do or modify.

Hide malware: Rootkits hide other types of malware on your device and make it difficult to remove.

Gain remote access: Rootkits provide remote access to your operating system while avoiding detection. Rootkit installations are increasingly associated with remote access scams.

Manipulate or disable security programs: Some rootkits can hide from your computer’s security programs or turn them off altogether, making malware detection and removal difficult.

Stealing data: Most of the time, cybercriminals use rootkits to steal data. Some hackers target individuals and collect personal data to commit identity theft or fraud. Others go after companies, either to spy on them or to commit financial crimes.

Create a permanent “backdoor”: Some rootkits can create a cybersecurity backdoor in your system that is left open for the hacker to return later.

Spying on you: Rootkits can be used as tracking tools that allow hackers to spy on you.

Invade your privacy: With a rootkit, a hacker can intercept your Internet traffic, record your keystrokes and even read your email.

Is a rootkit a virus?

A rootkit is not a virus per se. A computer virus is a program or piece of code designed to harm your computer by corrupting system files, wasting resources, destroying data, or simply being a nuisance. A key distinguishing feature of viruses is that they use your computer’s resources to reproduce themselves and spread through your files or to other computers without your consent.

Unlike viruses, rootkits are not necessarily harmful. What is dangerous is the different forms of malware that a rootkit can carry, which can then manipulate the operating system and provide administrator access to remote users. This makes them popular tools among cybercriminals, which is why rootkits have acquired such a bad reputation.

Where do rootkits come from and how do they spread?

Rootkits can come from a variety of sources and can be spread in different ways. Some common ways of acquiring and spreading rootkits include:

Exploitation of security vulnerabilities: rootkits are often installed through the exploitation of security vulnerabilities in the operating system or other software. Attackers can use automated tools to find and exploit known vulnerabilities in unpatched systems or security updates.

Programs downloaded from the Internet: Rootkits can also be hidden in programs or applications that users download from the Internet. Users may accidentally download the rootkit when downloading freeware or pirated programs.

Physical storage devices: Rootkits can also spread through physical storage devices such as USB drives or external hard disks. Users can accidentally infect their systems by connecting an infected device to their computer.

E-mail spam: Rootkits can also spread through spam email. Attackers may send emails with malicious links or attachments that install the rootkit when clicked.

It is important to use caution when downloading software from the Internet, connecting external devices to your computer and clicking on links or downloading suspicious email files to protect against rootkits and other malware threats. Keeping your operating system and software up to date can also help protect against security vulnerabilities that rootkits can exploit.

Types of rootkits

Security experts divide rootkits into six categories, based on the part of the computer infected and the depth of infection.

User-mode rootkits

User-mode rootkits infect your operating system’s administrator account and gain the top-level privileges needed to change your computer’s security protocols, while hiding themselves and any other malware they use.

These rootkits start automatically when you boot your computer, so a simple reboot is not enough to clean the infection. Malware scanning and removal programs such as Avast Free Antivirus can detect user-mode rootkits, as the rootkit detection software runs at a deeper level, known as the kernel.

Kernel-mode rootkits

In response to kernel-level rootkit scanners, hackers created kernel-mode rootkits. They reside at the same level of the computer as the operating system itself and therefore compromise that system completely.

When you get infected with a kernel-mode rootkit, there is nothing on your computer that you can trust: everything is potentially contaminated, including the results of any anti-rootkit scan. Fortunately, it is very difficult to create a kernel-mode rootkit that can operate without causing frequent system crashes and other performance problems that reveal its presence.

Hybrid rootkits

Hybrid rootkits put some of their components at the user level and others in the kernel. Thus, a hybrid rootkit enjoys the stability of user-mode rootkits, but with the enhanced stealth of their kernel cousins. As one might imagine, hybrid user and kernel rootkits are very popular with cybercriminals.

Firmware Rootkits

Firmware is a type of low-level software that controls a hardware element of the computer. Some rootkits can hide in the firmware when you turn off your computer. When you turn it back on, a firmware rootkit is able to reinstall itself and get back to work.

If a scanner finds and disables a firmware rootkit while it is running, the rootkit will reappear the next time you turn on the computer. It is quite complicated to purge a computer system of firmware rootkits.

Bootkits

When the computer is turned on, it queries the main boot record (MBR) for instructions on how to load the operating system. Bootkits, also known as bootloader rootkits, are a variant of the kernel-mode rootkit that infects your computer’s MBR. Whenever the computer queries the MBR, the bootkit is also loaded.

Antimalware programs have a hard time detecting bootkits, as with all kernel-mode rootkits, since they do not reside in the operating system. Fortunately, bootkits are obsolete because both Windows 8 and Windows 10 counter them with the Secure Boot feature.

Virtual Rootkits

A virtual machine is a software-based emulation of a stand-alone computer hosted on a physical computer. Virtual machines are used to run multiple operating systems on a single machine, or to test programs in an isolated environment.

Virtual rootkits, or virtual machine-based rootkits (VMBR), are loaded under the original operating system and then put that operating system into a virtual machine. Because they run independently of the computer’s operating system, they are very difficult to detect.

How to protect yourself against rootkits

Although some rootkits are stealthy and insidious, there are ways to avoid them. Often, the strategy to avoid rootkits is to practice healthy habits, which will protect against all types of threats:

Don’t open email attachments from unknown senders.

Do not download unknown files.

Make sure your system is properly patched against known vulnerabilities.

Be vigilant when installing software, make sure it is legitimate and that there are no red flags in the EULA (End User License Agreement).

Use external drives and USB sticks with caution.