What is a rootkit? How it works and how to protect yourself

Imagine someone broke into your house, hid inside your walls, and quietly watched everything you did. That’s essentially what a rootkit does to your computer.

Unlike typical viruses, rootkits are designed to stay invisible. They can remain undetected for weeks, months, or even years, giving cybercriminals control over your system while you have no idea anything is wrong.

The good news is that understanding how rootkits work makes them far easier to prevent. This guide breaks down what rootkits are, how they infect devices, the different types you should know about, and how to protect yourself.

A rootkit is a type of malicious software designed to give attackers hidden, privileged access to your device. The rootkit definition comes from two words:

Put them together, and you get a set of tools that grants attackers unrestricted root access to everything on your device.

Attackers use rootkits because they want persistent access. Rather than pulling off a quick data grab, they want to maintain privileged access to a system for as long as possible. This lets them steal information, install other malware, or use your device as part of a larger attack.

What separates rootkits from other malware is stealth. A virus corrupts files, a Trojan pretends to be legitimate software, and spyware records your activity. A rootkit can do all of those things, but its defining characteristic is that it hides the fact that any of it is happening.

Here’s an in-depth look at how rootkits compare to other common types of malicious software:

A rootkit attack typically follows four steps: infection, privilege escalation, concealment, and control. Here’s how each stage works.

Rootkit installation starts the same way most malware infections do. Common entry points include:

The key takeaway here is that most rootkit infections start with some form of social engineering or an unpatched system, both of which are often preventable.

Once on your device, the rootkit needs to escalate its permissions.

You see, a regular user account on your computer can browse the web and open files, but it can’t change core system settings. An administrator account can do much more: install software, modify system-level code, or turn off security features. A rootkit exploits software vulnerabilities or uses the permissions you granted during installation to gain administrative privileges.

Some rootkits go even further, embedding themselves directly into the operating system’s kernel, or the core code that controls how your hardware and software communicate. The kernel manages memory, processes, and every fundamental operation your computer performs. In other words, anything with access to it has near-complete control over the system.

The rootkit’s ability to conceal its activity is what makes it especially dangerous. Once a rootkit gains control, it actively works to evade detection by:

As a result of the above actions, your device behaves normally — even though an attacker is now controlling it.

With privileged access and full concealment in place, attackers can now:

Because the rootkit hides malicious processes from detection tools, this activity can continue for long periods without raising any alarms.

Where a rootkit resides in your system determines how deeply it can embed itself, how difficult it is to detect, and how much damage it can do.

Here are the most common types of rootkits:

User-mode rootkits operate in the part of your OS where your normal programs run. These rootkits typically replace or modify application files and software components to control how your programs communicate with the device’s system.

Because they don’t touch the core of the OS, user-mode rootkits are the easiest type to detect with standard antivirus programs. They’re also simpler for attackers to build, which makes them one of the most common types.

A kernel-mode rootkit operates at the deepest level of the operating system, known as the kernel space. This is where your OS manages hardware, memory, and every running process. By injecting malicious code directly into the kernel, these rootkits gain complete control over system behavior.

Kernel-mode rootkits can hide processes, files, and even entire drivers from security tools. They require administrative privileges to install, and removing them is notoriously difficult. In many cases, a complete system wipe combined with an OS reinstall is the only reliable solution.

Modern operating systems include defenses like driver signature enforcement and Secure Boot to make kernel rootkit installation harder, but attackers continue to find ways to bypass these protections.

Commonly called a bootkit, a bootloader rootkit infects the master boot record or other parts of the boot process that load your operating system at startup. Because bootkits activate before the OS even finishes loading, they can get around security software. In other words, a bootkit can compromise your system before antivirus programs, security features, or any other protective software has a chance to run.

Security features like Secure Boot were developed specifically to counter this type of threat and have made bootkits less common on modern hardware.

Firmware rootkits are among the hardest to detect and remove. They reside in hardware firmware, the low-level software that controls your device’s router, hard drive, or BIOS (the basic program that starts your computer before the operating system loads).

Because firmware sits below the operating system, standard rootkit scans and security tools rarely look there. Firmware rootkits can persist across reboots and OS reinstalls. If the rootkit resides in your device’s BIOS or router firmware, it can even survive a hard drive replacement.

A memory rootkit resides entirely in your device’s RAM. Because RAM is cleared every time you restart your computer, memory rootkits disappear after a reboot.

This can be good news because they don’t survive a restart. However, while they’re active, they can carry out significant damage without leaving obvious traces on your hard drive. They can also cause increased CPU usage and degraded performance.

Here’s a quick comparison of the different rootkit types:

Attackers can use a rootkit to do the following:

Rootkits are very difficult to detect by design, but infected systems sometimes show the following subtle warning signs:

These symptoms aren’t exclusive to rootkits and can also indicate other malware or hardware problems. But if you’re experiencing multiple signs at once, a deeper scan is worth running.

You can detect a rootkit by taking these steps:

Antivirus software with anti-rootkit capabilities can catch many threats, especially user-mode rootkits and rootkits that haven’t yet embedded deeply into your system. A dedicated rootkit scan searches for known attack signatures and hidden malicious processes that standard scans might miss.

No antivirus guarantees detection of every advanced rootkit. However, regular scanning significantly increases the chance of catching a rootkit infection early — before it has time to dig in.

Rootkits can control what your operating system sees, so kernel-mode rootkits and bootkits can hide from scans that run while your OS is active. Boot-time scans run before the OS fully loads, preventing the rootkit from hiding.

Many modern security tools offer offline or boot-time scan options specifically for this purpose. If you suspect a deep rootkit infection, this may be the most effective detection method.

Behavioral analysis can detect rootkit-like activities even when the rootkit itself can’t be directly identified. Look for:

Rootkit removal is often difficult. Manual removal is complex, and some kernel-level rootkits require a complete system wipe. That said, here’s a practical recovery checklist:

Preventing rootkit infections is much easier than removing them. These steps address avoiding the most common ways rootkits get onto devices:

Software updates close the security vulnerabilities that rootkits exploit.

When a known flaw goes unpatched, attackers can use it to inject malicious code and install rootkits without you clicking a single suspicious link. To minimize this risk, turn on automatic updates for your OS and all applications.

Cracked software, unofficial app stores, and random download sites are major vectors for rootkit malware. If you find something like a premium version of an app offered for free from a site you’ve never heard of, the deal is probably too good to be true. It likely comes packaged with something you don’t want, like a rootkit.

MFA won’t stop a rootkit from infecting your device, but it can limit the damage that’s done. If a rootkit steals your passwords via keystroke logging, MFA adds a second verification step that makes it harder for attackers to access your accounts with those stolen credentials.

Phishing remains one of the most common delivery methods for rootkits. Attackers send emails, texts, or DMs designed to trick you into clicking suspicious links, opening infected attachments, or entering your credentials on fake websites.

Before you click on anything, do the following:

Rootkits are just one piece of the broader cyberthreat picture. Reducing your overall risk means building multiple layers of protection, so if one layer is bypassed, others are still in place.

Invest in cybersecurity tools to help you:

Preventing threats like rootkits starts before malware ever reaches your device. Tools like Surfshark’s scam protection help identify potentially dangerous content, such as scam text messages, phishing emails, deceptive websites, and impersonation attempts.

Scam protection from Surfshark includes these tools:

Scam protection doesn’t detect or remove rootkits directly, but it can help you avoid the phishing attempts and scam tactics that attackers use to deliver malware.

Antivirus tools can detect and block many types of malware before they embed deeply into your system. For example, Surfshark Antivirus provides real-time protection and scans for malicious software, including rootkit malware.

No antivirus can guarantee detection of every advanced rootkit, but consistent scanning catches most threats before they gain a foothold.

Malware like rootkits can steal usernames, passwords, and other personal data. Data leak monitoring tools check if your private information has been exposed in known breaches.

Surfshark’s data leak monitoring notifies you if your details are found. You can then respond quickly by changing passwords and securing accounts before any of your stolen data is used against you.

While a VPN (Virtual Private Network) doesn’t detect or remove rootkits, it encrypts your internet traffic and masks your IP (Internet Protocol) address. This enhanced privacy a VPN provides is especially important on public Wi-Fi networks, where your data could be intercepted.

Encrypted connections from tools like Surfshark VPN make it harder for attackers to spy on your activity or use your network traffic as part of a larger attack.

Attackers often use publicly available personal information to craft more convincing phishing emails, impersonation attempts, and scam messages — the exact tactics used to deliver rootkits.

Data removal services like Incogni help reduce the amount of your personal information that data brokers can hold. With less of your sensitive information available on the internet, highly targeted social engineering attacks are much more difficult to construct.

Rootkits are some of the most dangerous and difficult-to-detect forms of malware, but they’re not unstoppable. Most infections start with a preventable action. By keeping your software up to date, avoiding phishing attempts, and using comprehensive cybersecurity tools, you can significantly reduce your risk.

Protect yourself across different stages of online threats with Surfshark One+. It’s a simple way to identify suspicious messages and websites, protect your devices against malware, monitor exposed personal information, and browse more privately.