What is a Rootkit?

Malicious software, known as a rootkit, is designed to get into a computer system without authorisation and to hide its presence.

Since rootkits are able to evade the detection of traditional antivirus software, they pose a significant threat and are challenging to remove. Their ability to alter system files, system calls, and other low-level processes to stay hidden for extended periods has earned them a stealthy reputation. Attackers have a significant weapon to control and influence compromised systems thanks to this capacity to function covertly.

Numerous varieties of rootkits exist, and they all target distinct system components. At the user level, user-mode rootkits are relatively simpler to identify and eliminate. However, kernel-mode rootkits are more dangerous since they operate at the core of the operating system, providing more control and deeper access. There are also more kinds, including firmware rootkits that target the BIOS or UEFI of the system and are very difficult to identify and remove, and bootkits that infect the master boot record or volume boot record to take control during the boot process.

Rootkits can open backdoors for attackers, giving them remote access and control over the compromised system by taking advantage of security flaws to obtain root or administrative-level access.

Various Types of Rootkits

Rootkits come in various types, each targeting different components of a computer system and operating at different levels of access.

1. User Mode Rootkits: These rootkits function at the user level within the system’s normal operational environment. Compared to other forms, they are simpler to find and eliminate because they have no impact on the operating system’s essential features. A user-mode rootkit may replace or alter installed system software to conceal its existence and carry out destructive behaviours.
2. Kernel Mode Rootkits: Deeper access and greater control over the system are made possible by kernel-mode rootkits, which operate at the core of the operating system. Since they can intercept and alter system calls, they are significantly more difficult to find and remove because their actions are hidden from both security software and the operating system. As a way to hide its presence and run commands with elevated privileges, a kernel-mode rootkit may modify kernel data structures or attach itself to the kernel.
3. Bootkits: Bootkits assume control during the boot process before the operating system is fully loaded by infecting either the Volume Boot Record (VBR) or the Master Boot Record (MBR). Due to these rootkits taking over early in the boot process, they can remain hidden from security software that loads later, making them difficult to detect. A malicious bootloader that loads the rootkit before the operating system boots up may be used by a bootkit to replace the genuine bootloader.
4. Firmware Rootkits: BIOS and UEFI firmware, which function at a level lower than the operating system, are the targets of firmware rootkits. They live in the firmware, which is not usually checked by standard antivirus software, making them hard to find and remove. A firmware rootkit can introduce malicious code into the BIOS firmware, ensuring that the rootkit is loaded again each time the computer boots up, even after the operating system has been reinstalled.
5. Hypervisor Rootkits (Virtualized Rootkits): These rootkits create a virtual environment where the operating system runs by installing itself within the operating system and making use of hardware virtualisation capabilities. They are practically undetectable to the operating system and traditional security measures due to their ability to intercept and influence low-level operations, which renders them very stealthy. A hypervisor rootkit can operate a virtualised version of the operating system, intercepting all hardware calls and secretly running its code.

Detecting and Removing Rootkits in Your System

Detecting and removing rootkits is a complex and challenging process due to their stealthy nature and deep integration with system components. However, several methods and tools can help in identifying and eliminating rootkits from an infected system.

1. Behavioural Analysis: A rootkit may be the cause of sudden crashes, poor performance, or strange network activities. Files and processes that are hidden or renamed may be signs of a rootkit infestation.
2. Rootkit Scanners: Use rootkit detecting programs to perform a system scan that can look for unusual activity and known rootkit signatures. Tools such as Tripwire can compare the system files’ present state to a well-established baseline to find unauthorised changes.
3. Memory Dump Analysis: Finding rootkits hidden from sight in the file system might be aided by examining the system memory for anomalies. Volatility and other similar tools can help with this investigation.
4. Boot-time Scanning: When rootkits hide during normal usage, antivirus software that enables boot-time scanning can help find them more easily by scanning the system before the operating system loads.
5. Log Analysis: Discovering anomalous activity or inaccuracies in system and security logs can offer hints regarding a rootkit infection.

Removing Rootkits

1. Use Specialised Removal Tools: Rootkit detection and removal can be aided by anti-rootkit software and tools. Manual removal, although risky and challenging, may require expert users to locate and remove harmful files and registry entries.
2. Reinstall the Operating System: Reinstalling the operating system is the most dependable way to get rid of a rootkit. Before doing this, make sure that any crucial data has been backed up and inspected for viruses. Additionally, formatting the hard drive ensures that the rootkit is completely removed, which is particularly important for firmware rootkits and bootkits.
3. Update Firmware: Updating the BIOS or UEFI firmware may help in removing malicious code from firmware rootkits. During this procedure, pay attention to the manufacturer’s instructions.
4. Secure Boot and Recovery Media: Rootkits can be prevented from loading during the boot phase by turning on Secure Boot in the BIOS or UEFI settings. Boot the computer from a clean and reliable recovery disc and perform antivirus and anti-rootkit checks.

Best Practices After Removal

1. Update the operating system, programs, and security software frequently to address vulnerabilities.
2. Use reliable antivirus and anti-malware software to conduct routine scans.
3. Continuously monitor the system for unusual behaviour to catch any signs of reinfection early.

Rootkits can be especially dangerous due to their ability to remain undetectable and persistent. To properly find and eliminate them, a multi-layered approach that includes both automated tools and manual examinations is often needed.

How can iZOOlogic help my Company or Organisation?

Find out how iZOOlogic can protect you against the threats of rootkits with the Financial Malware / Trojan Monitoring solutions.

To find out more about how iZOOlogic can help protect your company’s cyber security, schedule a demo.