Rootkits Malware: What Are They and How to Remove Them?

Malware Rootkits

Are you scared that your PC may have been infected by rootkits malware? It is one of the most persistent and challenging threats that frustrate many individuals and organizations. It is not a worm, virus, spyware, or even a Trojan. So, what is it? In a nutshell, rootkits are nasty programs that temporarily hide in your computer memory and run in kernel mode (ring 0 or protected mode) and user mode (ring 3).

One interesting thing about rootkits is that it tricks the user to think everything is working smoothly. You can liken them to a virtually invisible cloak whose main duty is to hide fraudsters’ activities that go on in the background. They are not only very hard to spot, but they are also challenging to remove. Your best bet to control rootkit infections is to understand them and prevent them from entering your system. What is important is to detect malicious attempts to install rootkits malware.

Rootkits History and Mission

The first rootkits have been with us for over two decades. Each year, they evolve in sophistication. Historically, they were confined to the world of Linux and UNIX, but over time, they made their way into the Windows operating system. Rootkits entered the Windows systems in 1999 through NTRootkit. Since then, they have entrenched themselves in Windows. In fact, they are available in the black market.

Rootkits’ main goal is to modify an operating system with the aim of hiding the malware that they are linked to from being discovered. They can lie dormant for an extended time, while other times, they can be used by nefarious individuals to ransack your computer. But in most cases, they may not do much damage to your system. Here, the malware does the actual damage in the background. In summary, rootkits are used to:

  • Hide other malware that hackers may install as part of a sustained attack.
  • Enhanced stealth, making it hard for anti-malware solutions and security professionals to detect the malware that the rootkit is protecting.
  • Provide a cybercriminal with unregulated access to your system, mainly through backdoors. Guarantee persistence, which allows the malware to survive most removal attempts by anti-malware products. In some instances, they may escalate the level at which the malware operates.
  • It turns the vulnerable computer into a member of a bot or a zombie computer.

Typically, rootkits are easy to install on your computer. To install a rootkit, a determined hacker can try any means possible to exploit a Windows vulnerability to get the physical system access or even crack a password. Once a rootkit has been injected into your system, the controller has the power to change system configurations and execute files remotely on the host computer. Sometimes, rootkits may trick users into running some executable files from email attachments. They may also spy on your computer usage.

Types of Rootkits

While there are many types of rootkits, only four are more common:

1. User-Mode Rootkits

As the name suggests, user-mode rootkits are usually created in a normal manner when you start your system. Sometimes, they may be injected into the system by a dropper. Actually, there are several other methods, which mainly depend on the operating system in use. User-mode rootkits focus on an entire application with a goal of replacing it entirely. In Windows, their main target is the basic functionalities of Windows DLL files.

Most user rootkits are paired with financial malware. One prominent example is Carberb, a financial malware that had its source code leaked some years back. Basically, its user-mode rootkit component has been copied several times and used by many financial malware families in modern times.

2. Kernel Rootkits

This type of rootkit changes the functionality of your OS. They achieve this goal by adding their own code to parts of your operating system core, usually known as the kernel. A good example of a kernel rootkit is SmartService, which rose to prominence in 2017. This virus blocks you from unleashing any antivirus tool, becoming an effective bodyguard for Trojan and adware infections.

It usually takes great skills to create kernel rootkits since they are fairly complex. Any mistake could make them easily noticeable. Of all the rootkits types, kernel rootkits are the easiest to discover.

3. Bootloader Rootkits

Bootkits or bootloader rootkits wreak havoc on the building block of your computer by infecting the Master Boot Record. For this reason, they are difficult to remove. If you are not careful, you could damage your computer while exterminating these rootkits.

Thankfully, recent Windows versions like Windows 10/11 and 8 have become immune to these rootkits, thanks to Secure Boot. So, these rootkits will soon become extinct. Prominent examples of these rootkits include the Alureon/TDL-4, which was very active from 2007 to 2012. During this time, Alureon became the second most active botnet before its developers were jailed.

4. Memory Rootkits

Memory rootkits are usually found in your PC’s memory (RAM). What differentiates them from other rootkits types is that they can stow away on your system for years without you noticing their presence. They will only be removed when you reboot your computer because your RAM’s content resets on startup.

How to Detect Rootkits?

As touched on earlier, it is not always easy to know if rootkits have settled on your computer. Nonetheless, here are notable rootkits symptoms:

  • Computer Lock: Your computer may fail to respond to any kind of input from the keyboard or mouse. It is usually the case if there is an installed kernel-mode rootkit.
  • Slow Performance and Unstable Network Activities: If your PC is painfully slow even when you are not running heavy programs, it could be a rootkit infection. Rootkits usually drain your computer memory. Besides this, your network or web activities may appear to be intermittent or malfunctioning because of excess network traffic.
  • Unexpected Changes: Settings in Windows may also change without your permission. A good example is a screensaver that keeps changing or the Taskbar hiding itself. Another example is unusual web browser behavior – for instance, your browser may add unrecognized bookmarks or redirects Google searches.
  • Blue Screen of Death (BSoD): If you are receiving error messages in white texts over a blue screen, there is a high possibility that you have got a rootkit virus infection.
  • Antivirus Deactivated: Has your antivirus program disabled itself, leaving your computer unprotected? This behavior is another sign of rootkit malware.
  • Inaccurate Clock and Date: Does your PC clock and date change each time you replace your device’s CMOS battery? Incorrect displays could be an indication of the virus at work.

However, if a rootkit is working properly, you are unlikely to see any of these rootkits symptoms. By design, rootkits are stealthy. Network slowdown should be a major red flag since they cannot hide traffic increases.

How to Remove Rootkits

You have several options to clean up rootkits:

#1: Scan Your System

The most effective way to remove the rootkit virus is to use a powerful antivirus program. Run a scan of your system using the antivirus. The process may take several hours, depending on the speed of your device.

Odds are that your everyday antivirus may not detect rootkits. That is why you should research for the right tools. Sometimes, you may need to work with multiple scanners to get rid of the virus. It is even better when you have a malware removal tool in your system to detect and delete the rootkit virus before it causes damage. Here are general-purpose scanners:

  • Rkill
  • TDSSKIller
  • RogueKIller
  • Outbyte Anti-Malware
  • Sysinternals’ RootkitRevealer
  • F-Secure Blacklight Rootkit Eliminator
  • Sophos Anti-Rootkit

Before running any of the above tools, reboot your infected device into Safe Mode. In this state, your PC will only run essential processes, making it possible for these tools to remove rootkits. To reboot your computer in Safe Mode, follow the steps below:

  1. Press the Windows + R shortcut, and then execute the msconfig command.
  2. Now, click on the Boot tab, then navigate to the Boot options section and check the Safe boot box.
  3. When you restart your computer, it will boot automatically into Safe Mode.

#2: Use System Restore

If you have created restore points in your Windows system, you can use the System Restore utility to revert to an earlier point before you picked up the rootkit malware. But you should be keen to pick a time you are sure your computer didn’t already have the virus.

But given the nefarious nature of this virus, you should reformat your computer to make sure you have deleted it completely.

#3: Removing Firmware Rootkits

Firmware rootkits are usually difficult to recover since they are embedded in a device’s firmware. They are persistent against both the replacement of the hardware and even the operating system. To protect yourself from such rootkits, ensure that your system’s firmware is up to date. More importantly, confirm that you are using Secure Boot. It has proved over the years that it can protect the preboot system by ensuring that only trustworthy codes can run this process.

To check if your PC is running in secure boot state:

  1. Go to the Start menu, then type System Information and press Enter.
  2. Look for the Secure boot state from the list of results.
  3. If it is present, then your system is currently running in this protected mode.

How to Prevent Rootkits

Many rootkits sneak into your computer by piggybacking with programs you trust or even a virus. But you can prevent a malware attack from happening if you follow the right strategies. One of the best ways to prevent rootkits malware is by having stricter signing requirements. Windows Secure Mode doesn’t allow untrusted binaries. Enabling the Windows Defender Device Guard will also ensure that you have extra protection. Besides this, use the following tips to minimize rootkit malware attacks:

  • Don’t Ignore Updates: The best way to safeguard your computer from rootkits is to ensure it is kept patched against identified vulnerabilities. The patches should cover your OS, up-to-date virus definitions, and applications.
  • Update Your Antivirus Program: Your security apparatus, including your antivirus software, should be up to date. Cybercriminals are becoming increasingly sophisticated and are releasing new virus definitions regularly.
  • Watch Out for Suspicious Website and Phishing Emails: Rootkits can get into your system through malicious websites, which usually have links that install malware on your computer. Clicking suspicious links could download a rootkit. You should also be careful when accepting and opening email attachments. Avoid interacting with documents from unknown sources.
  • Be Wary of New Software: Before you install any program, it is important to understand its source. You should only install software that you have read their licensing agreements. In most cases, less reputable developers or sites could include Trojans or rootkits in their offers. Freeware are usually bundled with malware and other programs with malicious intents, so they are riskier.
  • Clean up Your Computer: The longer you use your device, the more it accumulates files and other components that you might not need. Aside from taking up your system resources, some of them may even make it easier for malicious programs to get into the machine. But you should be careful not to delete important system files, as this could paralyze your computer. To avoid this mess, you can use reliable PC cleaner software.

Final Thoughts

Once you establish that your computer is infected, try rebuilding it using original software. It is better if you had kept restore points before the incident because it will help you roll back to an earlier working point. If you have no restore point, your next best trial is to clean up the mess using a suitable malware removal tool. Apart from the clean-up routine, you also need to reset the password for your system. More preferably, change the master password. Remember, the best way to manage rootkits is to lower your chances of being infected.

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