A rootkit is a piece of software usually malicious software that grants privileged, root-level (administrative) access to a computer while remaining undetectable on that system. Simply put, this is a nasty form of malware that really can seriously harm the performance of your PC and jeopardize your personal information.

Once it has been installed, a rootkit usually starts the computer’s boot process after the operating system does. However, some rootkits can start up before the intended operating system, which makes them very challenging to find.

The following are possible rootkit effects:

• Hidden malware: Rootkits give attackers the ability to install more malware on infected computers. They conceal harmful software from users as well as any anti-virus software that may be installed on their computer.
• Information theft – By using rootkits to install malicious software, hackers can steal sensitive data such as user passwords and credit card numbers without being noticed.
• File deletion – Rootkits can remove other files or operating system code from a system.

Rootkits can be used by hackers to eavesdrop on users and collect their data.

• File execution – Rootkits give hackers the ability to remotely execute both these files on target computers after subverting anti-malware software on the system.
• Remote access – Rootkits can change firewall settings to open backdoor TCP ports or startup scripts to change system configuration settings. This gives attackers remote access, enabling them to use a computer as part of a botnet, for example.

Even in the presence of active antivirus software, malware authors are interested in having their malicious code run continuously on a targeted host for extended periods. They must use a variety of techniques to thwart the detection and treatment of active infection for this purpose. They may make use of Operation System in both documented and undocumented ways. It is common knowledge that RootKits employ various methods of interception in both user mode and kernel mode, manipulations of objects (DKOM), methods of getting around filter drivers & callback functions, etc. RootKits must begin executing during the early stages of Operation System boot to infect boot sectors, such as Primary Boot Record (PBR) & Volume Boot Record, to support persistency upon that victim system (VBR). BootKit, which has this functionality, is a subset of rootkit  attack.

Combined threat

A rootkit cannot independently infect target computers. Attackers create a hybrid threat to exploit multiple vulnerabilities & infiltrate a system to spread a rootkit. The rootkit is combined with a loader and a dropper, two additional components, to accomplish this.

• A rootkit installation program or file is known as a “dropper” is used to set up a target computer with a rootkit. Droppers can be spread in a variety of ways such as through social engineering or a brute-force attack in which the perpetrator uses a program to repeatedly try to guess the root username and password of a system.
• Malicious code known as a loader is launched after a user starts the dropper program by opening or running a file. To ensure that the rootkit loads alongside the target system, the loader takes advantage of security flaws. For instance, a kernel-level rootkit may employ a loader that takes advantage of a flaw in Linux to swap out operating system code for a modified Loadable Kernel Module.

Rootkit varieties

Rootkits can be installed in a variety of ways on a target system. Several instances include:

• User-mode or application rootkits: These run at the application layer and are installed in shared libraries where they can alter the behavior of APIs and applications. Because they function at the same level as antivirus software, user-mode rootkits seem to be relatively simple to identify.These rootkits operate in kernel mode, where they can command all system processes because they are integrated into an operating system’s kernel module. Kernel-mode rootkits can affect the target system’s stability in addition to being challenging to detect.
• Bootkits – By infecting the target system’s master boot record, these rootkits take over (MBR). Through bootkits, a malicious program can run ahead of the target operating system. Rootkits that access the operating system of a device, such as a router, network card, hard drive, or system BIOS, are known as firmware rootkits.
• Hypervisor rootkits – These rootkits use the capabilities of hardware virtualization to take over a machine. Bypassing this same kernel or rather running the intended operating scheme in a virtual machine, is accomplished. Because they function at a greater level than the operating system and can intercept all hardware calls made by the target operating system, hypervisors are nearly impossible to identify and remove.

Measures to prevent rootkits

Scanning for existing malware and stopping the installation of new programs are two steps in the two-step process of protecting your systems from rootkit attack.

• Rootkit detectors

Scanners are applications created to parse a system and weed out rootkits that are currently active.

While scanners can aid in the detection and elimination of rootkits operating at the application layer, they are frequently ineffective against such operating at the kernel, boot, or firmware level. Only when the rootkit is not active can scanners that look for malicious code there at the kernel level be used. This implies that for a system to be effective, it must be started in the settings app with all system processes disabled.

• Anticipatory blocking

The concept behind rootkit prevention is that a rootkit can infect your system through both individual users and web-facing assets (i.e., websites).

Everyone in your organization needs to receive user education as the first preventative measure. This should include guidelines against downloading or opening files from unknown sources as well as instructions on how to spot malicious links and email attachments.

Additionally, users should be taught to recognize and steer clear of phishing schemes, in which malicious emails, websites, or files stealthily pretend to be from reputable sources. Particularly crucial for users with administrative rights.

 Anti rootkit protection is very vital for the sake of the smooth running of the software. Appsealing is one of the websites that can help people with software-related problems.