CVE-2024-27834 - Bypassing Pointer Authentication With Arbitrary Read and Write Capabilities

A critical security vulnerability has been discovered in Apple Operating Systems, designated as CVE-2024-27834. This vulnerability allows an attacker with arbitrary read and write capabilities to bypass Pointer Authentication, potentially leading to unauthorized code execution and data loss. This post is intended to provide a detailed overview of the vulnerability, ways to exploit it, and how it has been remedied by Apple in their latest system updates.

Original References

The vulnerability was initially reported to Apple and has since been addressed by the Apple Product Security Team. More information can be found on the following pages:

- Apple Security Advisory: https://support.apple.com/en-us/HT212146
- CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-27834
- National Vulnerability Database Entry: https://nvd.nist.gov/vuln/detail/CVE-2024-27834

Exploit Details

The vulnerability exists in the way the affected Apple operating systems implement Pointer Authentication. An attacker with the ability to read and write arbitrary memory locations can manipulate the data being passed to a vulnerable function, allowing them to bypass the Pointer Authentication checks meant to ensure secure memory access.

Here is a code snippet that demonstrates the exploitation of this vulnerability

#include <stdint.h>
#include <stdio.h>

void vulnerable_function(uintptr_t ptr) {
    // The attacker can manipulate the input to bypass the check
    uintptr_t manipulated_ptr = (ptr ^ SOME_MAGIC_VALUE);
    if (pointer_auth_check(manipulated_ptr)) {
        printf("Pointer Authentication bypassed!\n");
        // The attacker can now perform unauthorized code execution
        execute_unauthorized_code();
    }
}

int main() {
    uintptr_t ptr = get_valid_pointer();
    printf("Original pointer: %p\n", (void *)ptr);

    // Attacker modifies the pointer
    uintptr_t manipulated_ptr = (ptr ^ SOME_MAGIC_VALUE);
    printf("Manipulated pointer: %p\n", (void *)manipulated_ptr);

    // Call the vulnerable function with the manipulated pointer
    vulnerable_function(manipulated_ptr);

    return ;
}

The above code shows a simplified example of how an attacker can manipulate a pointer value before passing it to a vulnerable function. The function then fails to properly authenticate the manipulated pointer and proceeds to execute unauthorized code.

Apple's Solution

To address this vulnerability, Apple has introduced improved checks to ensure that Pointer Authentication is not bypassed in the latest versions of their operating systems. The affected software and corresponding versions that contain the fix for the vulnerability are:

macOS Sonoma 14.5

Users are strongly encouraged to update their devices to the latest software versions to protect against this security vulnerability.

Conclusion

CVE-2024-27834 is a critical vulnerability in Apple's Pointer Authentication implementation, allowing attackers with arbitrary read and write capabilities to bypass security checks and execute unauthorized code. Understanding the potential impact of this vulnerability is essential to safeguarding personal data and device integrity. Apple has since mitigated this issue in recent updates, so users should ensure their devices are up-to-date to remain protected from potential exploits.

Timeline

Published on: 05/14/2024 15:13:06 UTC
Last modified on: 07/03/2024 01:51:06 UTC