CVE-2023-42849: Bypassing Kernel Memory Mitigations with Improved Memory Handling

In this blog post, we will discuss the details of a recent critical vulnerability identified as CVE-2023-42849. The issue was addressed with improved memory handling, and it affects a wide range of Apple devices including iPhones, iPads, MacBooks, and Apple Watches. This vulnerability can potentially allow an attacker who has already achieved kernel code execution to bypass kernel memory mitigations.

Background

The vulnerability was discovered in various versions of Apple's operating systems - iOS 17.1 and iPadOS 17.1, macOS Monterey 12.7.1, watchOS 10.1, iOS 16.7.2 and iPadOS 16.7.2, macOS Ventura 13.6.1, and macOS Sonoma 14.1. The security issue is related to how the operating systems handle memory management, particularly in relation to the kernel. It was fixed in recent updates provided by Apple.

Vulnerability Details

In order to understand the exploit, we first have to look at what kernel memory mitigations are and how they work. Kernel memory mitigations are critical security mechanisms that protect the kernel (the core of the operating system) from being manipulated or compromised by malicious code.

When an attacker gains control over the kernel, they are able to execute code with the highest privileges, essentially taking complete control of the device. To protect against such attacks, operating systems implement a range of security measures, which include randomizing the location of kernel objects, isolating the kernel address space, and deploying various protection mechanisms to prevent the attacker from modifying the kernel memory.

The vulnerability identified as CVE-2023-42849, however, allows the attacker to bypass these kernel memory mitigations through exploitation of a memory handling flaw in the affected Apple operating systems.

To exploit this vulnerability, the attacker must first gain kernel code execution on the target device. This can be achieved through other existing exploits or vulnerabilities in the system. Once the attacker has achieved kernel code execution, they can then use this vulnerability to bypass kernel memory mitigations, ultimately compromising the security of the device.

Here's a simplified code snippet to give you a basic idea of how the exploit might work

// Kernel memory handling example

void vulnerable_function() {
    void *kernel_memory = allocate_memory();
    if (!kernel_memory) {
        // Memory allocation failed
        return;
    }

    read_data(kernel_memory);

    // Vulnerability: missing deallocation of kernel_memory
    return;
}

void exploit() {
    // Step 1: Gain kernel code execution
    gain_kernel_code_execution();

    // Step 2: Exploit memory handling flaw to bypass kernel memory mitigations
    while (true) {
        vulnerable_function();
    }
}

Links to Original References

The following links provide additional information and references related to this vulnerability. Please make sure to keep your devices updated to mitigate your exposure to this issue.

- CVE Details
- Apple Security Updates
- Exploit-DB Entry

Conclusion

In conclusion, CVE-2023-42849 is a serious vulnerability that affects a wide range of Apple devices. It allows an attacker with kernel code execution capabilities to bypass kernel memory mitigations, potentially compromising the security of the affected devices. To protect against this vulnerability, it is essential to apply the latest security updates provided by Apple for your device. Stay vigilant and ensure that your systems remain up-to-date to safeguard against ever-evolving security threats.

Timeline

Published on: 10/25/2023 19:15:10 UTC
Last modified on: 11/02/2023 18:16:45 UTC