CVE-2022-22591 is a critical memory corruption vulnerability that was found in Apple’s macOS kernel – the core layer that manages how apps interact with your Mac hardware. If exploited by a malicious application, this flaw could let an attacker run code with kernel privileges – the highest level of control possible. In short, an attacker could take control of the entire system.

Apple fixed this issue in macOS Monterey 12.2. If you are running a version before 12.2, you should update *right now*.

Let’s break down what happened, how it worked, and see some code snippets that demonstrate what makes this a real-world risk for Mac users.

The Problem: Memory Corruption in the Kernel

When software messes up how it handles memory, this sometimes lets attackers sneak their own code into privileged areas. In CVE-2022-22591, a “malicious application” could exploit a memory handling bug in the macOS kernel to run its own commands with kernel-level access.

Apple’s official advisory describes it simply

> A memory corruption issue was addressed with improved memory handling. This issue is fixed in macOS Monterey 12.2. A malicious application may be able to execute arbitrary code with kernel privileges.

The Vulnerability: Under the Hood

Apple hasn’t published all the details, but independent researchers and the MITRE CVE record show that this bug involved how the macOS kernel handled certain user input or data from applications.

At a high level, the problem was: Insufficient checking or mishandling of memory boundaries in kernel code. This is a classic ‘buffer overflow’ or ‘use-after-free’ style bug.

Example Scenario

Imagine a kernel interface function that copies data from user memory to the kernel, but fails to properly validate sizes:

// Hypothetical vulnerable macOS kernel code
int vulnerable_kernel_function(user_buffer *ubuf, size_t len) {
    char kernel_buf[64];

    if (len > 64) len = 64; // supposed check, but let's say there's a bug...

    memcpy(kernel_buf, ubuf->data, len); // Potential overflow if len isn't correct

    // processing kernel_buf...
    return ;
}

If the *check* fails or can be bypassed, a malicious program can send more data than kernel_buf can hold, overwriting precious memory — possibly *return addresses* or *pointers* used by the kernel. From there, an attacker can change the course of execution.

Proof of Concept: Exploit Overview

While there isn't a public full exploit (since this is very dangerous), here’s an outline of how such an attack could be carried out:

Trigger Memory Corruption

- The corrupted memory region may overwrite pointers, data structures, or even function return addresses within the kernel.

Achieve Code Execution in Kernel

- By controlling what the corrupted memory points to, the attacker makes the kernel “jump” to their own code.

Proof-of-Concept in Pseudo-Code

// USER APPLICATION
#include <stdio.h>
#include <string.h>

// Call into a vulnerable syscall or kernel extension
void trigger_exploit() {
    char evil_buffer[128];
    memset(evil_buffer, 'A', sizeof(evil_buffer));

    // some payload to redirect execution
    *(uint64_t*)(evil_buffer + 72) = xdeadbeefcafebabe;

    // Hypothetical IOCTL to vulnerable kernel function
    int fd = open("/dev/vuln_device", 2);
    ioctl(fd, CMD_DO_SOMETHING, evil_buffer); // oversized buffer!
}

int main() {
    trigger_exploit();
    return ;
}

*Note: This is demonstration code only — actual attacks target real-life kernel interfaces.*

You can see in Apple’s security notes

> *“A memory corruption issue was addressed with improved memory handling. This issue is fixed in macOS Monterey 12.2.”*

Even sandboxed apps, in some cases

Privilege escalation to kernel is about as serious as a local bug can get.

References

- Apple Security Update 2022-001: Monterey 12.2
- CVE-2022-22591 on MITRE
- Apple Kernel Security
- Understanding Kernel Exploits

Conclusion

*CVE-2022-22591* is a reminder that memory safety is still vital even on highly locked-down operating systems like macOS. While Apple moved quickly to patch this bug, attackers are always looking for new ways to misuse bugs like these. The best defense is staying updated and knowing how these threats work.

If you want to learn more, check out Apple’s official security updates and follow security news to keep your devices safe!

Timeline

Published on: 03/18/2022 18:15:00 UTC
Last modified on: 03/26/2022 03:58:00 UTC