Privilege Escalation by kernel vulnerability - ties2/Red-Team GitHub Wiki

Privilege escalation is one of the most common techniques used by hackers to gain higher levels of access to a system. It is often achieved through exploiting vulnerabilities in the operating system or software applications. Kernel vulnerabilities are one such class of vulnerabilities that can be used for privilege escalation. A kernel is the core component of an operating system that is responsible for managing system resources and executing user programs. In this essay, we will explore the concept of kernel vulnerabilities and how they can be used for privilege escalation. We will provide examples of kernel vulnerabilities and the techniques used by hackers to exploit them. Finally, we will discuss ways to prevent kernel vulnerabilities and the importance of keeping systems up-to-date.

Understanding Kernel Vulnerabilities

A kernel vulnerability is a flaw in the kernel that can be exploited to gain unauthorized access to a system. These vulnerabilities can exist in any operating system, including Windows, Linux, and macOS. The severity of a kernel vulnerability depends on the level of access it provides to the attacker. In some cases, a kernel vulnerability may allow an attacker to execute arbitrary code with kernel-level privileges, which provides them with complete control over the system.

Kernel vulnerabilities are often discovered by security researchers who conduct vulnerability assessments on operating systems and software applications. Once a vulnerability is discovered, it is usually reported to the vendor who is responsible for providing a fix. However, in some cases, hackers may discover these vulnerabilities before the vendor and use them for malicious purposes.

Exploiting Kernel Vulnerabilities for Privilege Escalation

Kernel vulnerabilities can be exploited for privilege escalation by attackers. An attacker with user-level access to a system can use a kernel vulnerability to gain higher-level access to the system. Once the attacker gains access at a higher level, they can perform actions that are not possible at the lower level, such as installing malware, stealing sensitive information, or modifying system configurations.

There are several techniques that attackers use to exploit kernel vulnerabilities for privilege escalation. These techniques include:

Use of Kernel Modules: A kernel module is a piece of code that can be loaded and unloaded dynamically into the kernel at runtime. Attackers can use kernel modules to exploit vulnerabilities in the kernel. They can load a malicious kernel module into the kernel, which allows them to execute code with kernel-level privileges.

Buffer Overflow: A buffer overflow is a type of vulnerability where an attacker can overwrite data in a buffer and execute arbitrary code. Attackers can use buffer overflow vulnerabilities in the kernel to gain kernel-level privileges.

Integer Overflow: An integer overflow is a type of vulnerability where an attacker can manipulate an integer variable to cause unexpected behavior in the program. Attackers can use integer overflow vulnerabilities in the kernel to gain kernel-level privileges.

Race Conditions: A race condition is a type of vulnerability where an attacker can manipulate the timing of events to cause unexpected behavior in the program. Attackers can use race condition vulnerabilities in the kernel to gain kernel-level privileges.

Examples of Kernel Vulnerabilities

Here are some examples of kernel vulnerabilities that have been discovered in the past:

Windows XP Kernel Vulnerability: In 2013, a vulnerability was discovered in the kernel of Windows XP that allowed an attacker to gain kernel-level privileges. The vulnerability was caused by a buffer overflow in the win32k.sys driver. An attacker could exploit this vulnerability by creating a specially crafted font file and convincing a user to open it. Once the font file was opened, the attacker could execute arbitrary code with kernel-level privileges.

Linux Kernel Vulnerability: In 2016, a vulnerability was discovered in the Linux kernel that allowed an attacker to gain kernel-level privileges. The vulnerability was caused by a race condition in the keyring subsystem. An attacker could exploit this vulnerability by running a specially crafted program on the target system. Once the program was executed, the attacker