CVE-2023-23507: Improved Bounds Checks Fix Security Flaw Allowing Arbitrary Code Execution with Kernel Privileges in macOS

A recently discovered vulnerability, registered as CVE-2023-23507, caught the attention of cybersecurity researchers and professionals worldwide. The security flaw affected macOS systems and allowed arbitrary code execution with kernel privileges, which could potentially be exploited by an attacker to conduct malicious activities on the targeted device. Thanks to the swift resolution by Apple, users can now rest assured that the vulnerability is no longer a threat in macOS Ventura 13.2 and macOS Monterey 12.6.3, as the issue has been addressed with improved bounds checks.

This blog post will give you an in-depth insight into the CVE-2023-23507 vulnerability, its exploit details, the code snippets involved, and a detailed guideline on how to fix the problem by updating your macOS system.

Exploit Details

The discovery of this vulnerability in macOS systems indicates that an app might exploit the flaw and execute arbitrary code with kernel privileges. Kernel privileges are critical as they provide access to the heart of an operating system, which means that any malicious activity using these privileges could severely compromise the entire system.

The issue was mainly caused due to insufficient bounds checks, which allowed an attacker to gain unauthorized access and execute arbitrary code with kernel privileges. Once an attacker accomplished this, they could potentially modify, bypass, or disable security measures, deploy malware, exfiltrate sensitive data, and perform other malicious operations.

A code snippet illustrating the issue prior to the fix might look like this

int faulty_bounds_check(void *input) {
    int buffer[32];
    int index = get_index(input);
    int value = get_value(input);

    if (index < 32) {
        buffer[index] = value;
        return ;
    } else {
        return 1;
    }
}

The problem in the code above lies in the insufficient bounds check, as it only checks whether the 'index' variable is less than 32. However, a proper bounds check should also verify if the 'index' variable is within the acceptable range (i.e., greater than or equal to ) to prevent potential memory corruption or access violations.

The improved bounds check would look like this

int secure_bounds_check(void *input) {
    int buffer[32];
    int index = get_index(input);
    int value = get_value(input);

    if (index >=  && index < 32) {
        buffer[index] = value;
        return ;
    } else {
        return 1;
    }
}

Links to Original References

Apple has acknowledged the security vulnerability and has mentioned it in their official security documentation:
- Apple security support document

The National Vulnerability Database (NVD) has also published the CVE-2023-23507 details on their website:
- NVD CVE-2023-23507 vulnerability details

How to Fix the Issue

To fix the CVE-2023-23507 issue and protect your macOS system from potential exploitation, you should update your macOS to the latest released version. For macOS Ventura users, upgrade to version 13.2, and for macOS Monterey users, update to version 12.6.3. To update your macOS, follow these steps:

Conclusion

Keeping your system updated is essential for ensuring its security against constantly evolving threats. By addressing CVE-2023-23507 with improved bounds checks, Apple has essentially protected its macOS users from a potentially severe vulnerability that posed a significant risk to system security. We encourage users to update their systems regularly and stay informed about emerging threats and vulnerabilities to safeguard their devices and data from cyber-attacks.

Timeline

Published on: 02/27/2023 20:15:00 UTC
Last modified on: 03/04/2023 02:04:00 UTC