Demystifying Linux Kernel Security: The Need for Linux Kernel Patching

Rohan Timalsina

August 9, 2023 - TuxCare expert team

The Linux kernel is the core of the Linux operating system, serving as a bridge between computer hardware and the software programs that run on it. It is responsible for managing system resources, including the CPU, memory, and peripherals. Given its critical role, any vulnerability within the Linux kernel could pose a significant risk to the entire infrastructure.

This article will explain the Linux kernel, how it handles security, as well as why it is essential to patch the Linux kernel for the system’s overall security.

Linux Kernel Security Features

For any Linux system administrator aiming to uphold a secure and reliable environment, gaining insight into the inner workings of the Linux kernel and its security features is essential. Linux boasts several kernel security features that set it apart from other operating systems, contributing to its enhanced security.

User and Kernel Space Isolation: The separation of user space and kernel space stops user-level applications from harming the kernel and other processes or interfering with them. Unauthorized access is also prevented if the user space code tries to access kernel space directly.

Memory Protection: The Linux kernel applies memory protection via Memory Management Units (MMUs). Each process is given a virtual memory area by the MMU, which keeps them separate from one another. The MMU causes a segmentation error if a process tries to access memory that is not part of its assigned region, guarding against any security lapses.

User Permissions: Linux implements a strong permissions model that provides users and processes with different levels of access. The key elements of this architecture are file ownership and permissions. These permissions are enforced by the kernel, preventing unauthorized users and groups from accessing files and folders.

ASLR: A built-in security technique, Address Space Layout Randomization (ASLR) defends the system against buffer overflow attacks. Every time the system boots, it randomly allocates the memory address area of the running processes, making it difficult for hackers to predict where memory would be used to execute malicious code.

Kernel Auditing: Linux provides the ability to audit kernel activity through the use of programs like auditd, allowing for the monitoring of security-related kernel events. Kernel auditing assists in monitoring system changes, user activity, and potential security breaches when configured properly.

Secure Boot: Secure Boot, which makes sure that only signed and trustworthy software, including the kernel, can run during the boot process, is supported by a large number of contemporary Linux systems. By preventing rootkits and bootkits from interfering with the boot process, this feature defends against them.

Seccomp: Secure Computing Mode is a potent security technique that limits the number of system calls a process is allowed to make. It dramatically decreases the attack surface of the kernel, reducing the effect of potential weaknesses in certain system functions.

Linux Security Module: LSM (Linux Security Module) offers a framework that allows the integration of additional security modules in the Linux kernel. These modules can increase the security features of the kernel and provide administrators with more control over access restriction and policy implementation.

Additional Practices to Improve the Security

While there are Linux kernel security features, following these methods can help enhance your Linux kernel security.

Regular Updates: Stay updated with new kernel updates as they frequently come with security patches to fix discovered vulnerabilities. Maintain system updates to provide the most recent security enhancements.

Least Privilege Principle: When granting a user permission, follow the principle of least privilege. Ensure that users only have access to the resources required for their jobs to reduce the possible harm in the event of a security breach.

Firewalls and SELinux: To further enhance your system’s defenses, use SELinux (Security-Enhanced Linux) to implement required access controls in addition to firewalls to manage network traffic.

Kernel Patching: Apply kernel security patches to mitigate known vulnerabilities and prevent malicious exploitation of the system.

Linux Kernel Security Vulnerabilities

This year in 2023, the Linux Kernel has been identified with a total of 176 vulnerabilities, with an average severity score of 6.5. Comparing this to the previous year, which saw 309 security vulnerabilities reported, it indicates that the number of security issues in the Linux Kernel for 2023 might exceed the figure from the previous year if the current trend continues. (Source: stack.watch)

Linux kernel security vulnerabilities are a significant concern for the developers and users of the Linux operating system. These are some possible reasons that can lead to the existence of security vulnerabilities in the Linux kernel.

The Linux Kernel is a huge and complex piece of software with millions of code lines. It becomes more difficult to verify there are no errors that could result in security risks when things are this complicated.

We all know that the Linux kernel adopts a continuous development process with frequently adding new features and updates. While these changes bring improvements, they sometimes also result in unexpected security exploits.

The Linux Kernel also contains code from different sources, such as drivers and other modules. Integrating code from many third-party sources might unintentionally introduce security flaws.

When developers are under pressure to release new versions quickly, full security evaluations may suffer, potentially creating vulnerabilities. Despite thorough testing, some vulnerabilities may still be missed, even by experienced developers.

Security researchers and the Linux community are active and quick to notify the Linux Kernel maintainers as soon as vulnerabilities are found. The developers then put forth great effort to provide patches or updates that address these flaws, making sure that the users can protect their systems from associated risks.

Conclusion: KernelCare for Patching the Linux Kernel

Security vulnerabilities could remain unaddressed without proper kernel patching, exposing the system to potential attacks. Cybercriminals actively search for unpatched systems to exploit known vulnerabilities and gain unauthorized access, leading to severe consequences such as data breaches, system compromise, and even complete system takeover.

A secure kernel protects your personal data, keeps your computer functioning properly, and guards it from viruses and hackers. Thus, the need for timely patching of the Linux kernel becomes paramount for maintaining a secure computing environment and lowering the risk of potential vulnerabilities that cybercriminals might take advantage of.

However, applying a kernel patch often requires a system reboot or downtime, which is not acceptable for enterprise servers. In such cases, live kernel patching is more suitable as system administrators can apply patches to the running kernel without having to reboot or face downtime. That’s exactly what TuxCare’s KernelCare Enterprise offers.

KernelCare provides automated live patching solutions for all popular Linux distributions, including RHEL, Debian, Ubuntu, CentOS, AlmaLinux, RockyLinux, Oracle Linux, and more. For all supported kernels and distributions, please refer to this article.

Summary