The root cause is to completely remove the rootkit.

Article Title: Root-sourcing is to completely remove rootkit. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.
In this technical guide, you will learn that rootkit is difficult to detect and allows hackers to have full control over your system. Find out how these hacking tools are used and how to find the rootkit hidden in your system.
　　
Suppose you are a hacker. You just found that a system is not your opponent of the "leet skillz" tool software and has obtained root access permissions. The system administrator may later find that his system is "owned" by others. You are kicked out after the system uses a patch for repair. This is why you want to install rootkit. Rootkit is software installed by hackers in the system to help restore the permissions of hackers in the system. Most rootkits also contain other advanced tools, such as helping hackers build backdoors to continuously access compromised computer systems. For example, the rootkit can intercept login requests and allow hackers to access them secretly using a special user ID and password. Key recorder, package sniffer, and other code that exploits security vulnerabilities are common in rootkit.
　　
　　 Concealed attacks
　　
Rootkit can be hidden by hiding or deleting logon records, registry records, and traces of processes related to hacker activity. Some rootkits replace binary commands in system management commands with modified commands designed to ignore hacker operation commands. For example, in Unix or Linux systems, rootkit replaces the "ls" command with a command that cannot display the list of files in some directories. Alternatively, the hacker uses a command to ignore the hacker activity process to replace the "ps" command. The "ps" command is used to display processes running in the system. The program responsible for recording activities will also be modified to help attackers hide and avoid suspicion. Therefore, when the system administrator looks at the system, everything looks normal, even though the system has been overturned by hackers.
　　
　　 Rootkit Style
　　
The rootkit that completes the task by modifying the Binary command is called the user mode rootkit. These rootkits can be identified by checking the size, date, and checksum of critical system files.
　　
However, advanced hackers use the kernel mode rootkit to work more concealed. By using Linux to load kernel extensions during running, the kernel mode rootkit can fool the kernel of the operating system. These rootkits are quietly hidden in the heart of the computer and intercept calls from legitimate applications to the operating system. They only return the date that the attacker will show you. This rootkit controls the entire system environment, and it is very difficult to identify this rootkit.
　　
Although rootkit is developed in the Unix/Linux field, many existing rootkits are available in the Windows environment to provide the same functions as the Unix/Linux rootkit.
　　
Some Windows rootkit are very advanced. For more information about these advanced Windows rootkit, visit www.rootkit.com. If you are responsible for Windows system security, spending some time on this website will make you more vigilant.
　　
　　 Preventive actions
　　
Rootkit is the second-level security threat. In other words, you must first make some security errors to allow attackers to access your system, such as configuration errors, weak identification, or no security vulnerabilities. Once the rootkit enters your system, a very bad thing will happen. What is the best way to defend against rootkit? First, implement a defense-in-depth strategy to prevent rootkit from being installed in your system.