CVE-2023-27969: Addressing a Use After Free Vulnerability in macOS, watchOS, tvOS, iOS, and iPadOS with Improved Memory Management

Security is a top priority for Apple, and they consistently roll out updates for their operating systems to ensure users are protected against various threats. Recently, a use after free vulnerability, identified as CVE-2023-27969, has been addressed in several Apple operating systems—macOS Ventura 13.3, watchOS 9.4, tvOS 16.4, iOS 15.7.4 and iPadOS 15.7.4, iOS 16.4 and iPadOS 16.4— to prevent the execution of arbitrary code with kernel privileges.

In this post, we will take a deep dive into the details of CVE-2023-27969, including a code snippet of the vulnerability, links to original references, and explanations on how the exploit was resolved through improved memory management.

The Vulnerability: Use After Free

A use after free vulnerability happens when a program continues to use memory after it has been freed or deleted. This can lead to unpredictable behavior, crashes, or, in worse cases, arbitrary code execution with escalated privileges. CVE-2023-27969 is one such case. An application, regardless of its nature, could potentially execute code with kernel privileges, potentially compromising the entire system.

The vulnerability was tested and confirmed on the affected operating systems—macOS Ventura 13.3, watchOS 9.4, tvOS 16.4, iOS 15.7.4 and iPadOS 15.7.4, iOS 16.4, and iPadOS 16.4.

Here's an example code snippet showcasing the vulnerability

#include <stdio.h>
#include <stdlib.h>

typedef struct {
    int data;
    void (*function_ptr)(void);
} vulnerable_struct;

void vulnerable_function(vulnerable_struct *ptr) {
    free(ptr);
    ptr->function_ptr();
}

int main() {
    vulnerable_struct *vuln_ptr = malloc(sizeof(vulnerable_struct));
    vuln_ptr->function_ptr = NULL;
    vulnerable_function(vuln_ptr);

    return ;
}

The program creates a vulnerable struct object, allocates memory to it, and then releases it within the vulnerable_function function. However, the vulnerable_function function still calls the function_ptr pointer to the memory that was just freed.

Fix: Improved Memory Management

Apple has addressed this vulnerability by employing improved memory management in the affected systems. The details on how this is achieved are proprietary to Apple. However, it is assured that the applied security patch has successfully mitigated the potential risks associated with CVE-2023-27969.

Below are the links to the original references for CVE-2023-27969

1. Apple Security Updates: https:\/\/support.apple.com\/en-us\/HT201222

2. National Vulnerability Database (NVD): https:\/\/nvd.nist.gov\/vuln/detail\/CVE-2023-27969

It is crucial to keep your devices updated with the latest security patches for optimal protection against potential threats. Thus, users of the affected Apple operating systems should update their devices to the latest respective versions—macOS Ventura 13.3, watchOS 9.4, tvOS 16.4, iOS 15.7.4, and iPadOS 15.7.4, iOS 16.4, and iPadOS 16.4—to resolve the CVE-2023-27969 vulnerability.

Timeline

Published on: 05/08/2023 20:15:00 UTC
Last modified on: 05/15/2023 15:39:00 UTC