1. Introduction to Linux Kernel Exploitation

Introduction to Linux Kernel Exploitation

Overview of kernel space vs. user space

Kernel space and user space are two distinct memory regions in a computer's operating system.

• Kernel space: This is the privileged mode of the operating system where the kernel code and critical system data reside. Processes running in kernel space have unrestricted access to hardware and system resources.
• User space: In contrast, user space is where regular user programs execute. Processes in user space have limited access to system resources and rely on system calls to interact with the kernel.

Understanding kernel vulnerabilities

Kernel vulnerabilities are flaws or weaknesses in the design or implementation of the Linux kernel that can be exploited by attackers to gain unauthorized access or control over a system.

• Types of kernel vulnerabilities: These can range from memory corruption issues such as buffer overflows and use-after-free errors to logic flaws and privilege escalation vulnerabilities.
• Common attack vectors: Attackers often exploit kernel vulnerabilities through various techniques such as stack smashing, heap spraying, and race conditions.

Introduction to exploit development

Exploit development involves the creation of software tools or code snippets that leverage kernel vulnerabilities to achieve specific goals, such as gaining root privileges or executing arbitrary code.

• Components of an exploit: An exploit typically consists of payload code, shellcode, and exploit techniques tailored to the specific vulnerability being targeted.
• Development process: Exploit development follows a systematic process of vulnerability discovery, analysis, and crafting of exploit code.

Lab Activities

Buffer Overflow Exploit

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void vulnerable_function(char *input) {
    char buffer[64];
    strcpy(buffer, input);
}

int main(int argc, char **argv) {
    if (argc != 2) {
        printf("Usage: %s <input>\n", argv[0]);
        exit(EXIT_FAILURE);
    }
    
    vulnerable_function(argv[1]);
    return 0;
}

In this lab activity, we'll exploit a buffer overflow vulnerability in the vulnerable_function().