In June 2024, Apple disclosed a high-severity kernel vulnerability tracked as CVE-2024-54529 affecting macOS. This bug, stemming from a logic flaw in kernel checks, allowed a malicious app to execute arbitrary code with kernel privileges—essentially giving attackers full control over the device. In this article, we break down what this bug is, how it can be exploited, give code snippets to clarify the concept, and share how you should protect yourself.

This vulnerability is described by Apple as

> “A logic issue was addressed with improved checks. This issue is fixed in macOS Sequoia 15.2, macOS Ventura 13.7.2, and macOS Sonoma 14.7.2. An app may be able to execute arbitrary code with kernel privileges.”
>
> — Apple Security Updates, June 2024

In short, a flaw in kernel logic allowed untrusted apps far more access than intended.

The kernel failed to properly validate input or execution flow in certain requests from user space.

- A malicious app could send specially crafted requests (for example, IOCTL calls) that tricked the kernel into executing uncontrolled code.

Simple Reproduction Example

A common source of such vulnerabilities is where an input isn’t properly checked before use. Here’s a *pseudo-code* snippet to illustrate:

// a vulnerable kernel routine (hypothetical)
int vulnerable_function(user_input) {
    if (user_input->length < MAX_SIZE) {
        memcpy(kernel_buffer, user_input->data, user_input->length);
        // logic error: doesn't check if user_input->data points where it should
    }
    // ...
}

Logic issue: The function checks the length, but does not check where the input pointer actually points. An attacker could craft user_input->data to point anywhere in memory—allowing kernel memory corruption and code execution.

Step-by-step exploit summary

1. Craft a Malicious App: Create an executable that opens the vulnerable device (for example /dev/vulndev).
2. Prepare a Malicious Payload: User space code prepares a buffer that simulates valid input but sets pointers or data that, when interpreted by the kernel, breaks memory safety.
3. Trigger the Bug: Send the payload to the vulnerable kernel function, which doesn’t properly check the logic and executes the malicious code.
4. Achieve Kernel Privileges: If successful, the exploit can modify kernel memory or execute arbitrary code, gaining root and kernel privileges.

Proof-of-Concept (PoC) Example

*Note: This code cannot be compiled or run on actual macOS; it’s for illustration.*

#include <fcntl.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <string.h>
#include <unistd.h>

#define DEVICE "/dev/vulndev"
#define IOCTL_CODE xdeadbeef // hypothetical code

struct exploit_buffer {
    size_t length;
    void *data;
};

int main() {
    int fd = open(DEVICE, O_RDWR);
    if (fd < ) {
        perror("open");
        return 1;
    }
    char malicious_data[16];
    memset(malicious_data, 'A', 16);
    struct exploit_buffer buf = {
        .length = 16,
        .data = (void*)xffffff800000000 // kernel memory address
    };
    ioctl(fd, IOCTL_CODE, &buf);
    close(fd);
    return ;
}

Here data points to a kernel address. If kernel routines fail to check this, the call could overwrite or execute in kernel space.

macOS Sequoia before 15.2

*If you have not updated after June 2024, your machine may be at risk.*

Staying Safe

- Update macOS: Go to Apple Menu > System Settings > General > Software Update. Install the latest available version for your macOS branch.
- Audit and Remove Untrusted Apps: Don’t install untrusted third-party apps, especially those requiring elevated permissions.
- Check Apple’s Security Portal: Apple security updates

References

- Apple security updates: June 2024
- Official CVE entry for CVE-2024-54529
- macOS Security Updates

Bottom Line

CVE-2024-54529 is proof that even mature OS kernels can suffer from simple logic issues with huge consequences. With kernel-level bugs, the ability to execute arbitrary code allows complete compromise of Apple devices. Updates are available—don't delay patching your system.

Timeline

Published on: 12/12/2024 02:15:32 UTC
Last modified on: 12/20/2024 14:47:44 UTC