CVE-2022-32940 - Arbitrary Code Execution with Kernel Privileges: Mitigated by Improved Bounds Checks in tvOS 16.1, iOS 16.1, iPadOS 16, macOS Ventura 13, and watchOS 9.1

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In this post, we will thoroughly discuss the recently identified security vulnerability - CVE-2022-32940, its effect on multiple Apple operating systems, and the means by which this vulnerability allows an app to execute arbitrary code with kernel privileges. Furthermore, we will delve into the fixes rolled out by Apple to mitigate this issue in their latest release of tvOS 16.1, iOS 16.1, iPadOS 16, macOS Ventura 13, and watchOS 9.1.

Background of the vulnerability

CVE-2022-32940 is a critical security flaw that pertains to poor bounds-checking in several Apple operating systems. In a nutshell, bounds-checking is responsible for ensuring that a program does not attempt to access memory locations beyond its allocated limits. However, due to an error in the bounds-checking mechanism in these systems, an app could potentially execute arbitrary code with kernel-level privileges.

Exploit Details

When exploiting this vulnerability, a malicious app can interact with the compromised bounds-checking mechanism to carry out unintended operations and bypass security measures put in place. Consequently, the app is capable of executing arbitrary code, even with kernel privileges, which ultimately heightens the level of access and control over the affected system.

To further illustrate the technical specifics, let's take a look at a code snippet that demonstrates the flaw in bounds-checking:

int transfer_data(char *src, char *dst, unsigned int size) {
  int status = ;
  
  if (size > BUFFER_SIZE) {
    printf("Error: Data size exceeds buffer limits.\n");
    status = -1;
    return status;
  }

  memcpy(dst, src, size);

  return status;
}

In the transfer_data function above, the bounds-checking mechanism fails to properly validate the size of the data being transferred (size), permitting an attacker to exploit the bounds checks and manipulate the memcpy() function's size parameter. Consequently, this poor bounds-checking mechanism allows an app to execute arbitrary code with kernel privileges.

Links to Original References

Below are the links to Apple's official security advisories and updates, which discuss the vulnerability in detail, as well as the recommended updates:

1. tvOS 16.1 Release Notes
2. iOS 16.1 and iPadOS 16 Release Notes
3. macOS Ventura 13 Release Notes
4. watchOS 9.1 Release Notes

The Fix: Improved Bounds Checks

Apple identified the issue and addressed it promptly in its latest updates by improving the bounds-checking mechanisms. The new bounds checks effectively prevent a malicious app from manipulating or bypassing the system's built-in security features, thereby eliminating the possibility of arbitrary code execution with kernel privileges.

To secure your system(s) against CVE-2022-32940 and other potential threats, it is crucial to ensure you update to the latest versions of Apple's operating systems, namely tvOS 16.1, iOS 16.1 and iPadOS 16, macOS Ventura 13, and watchOS 9.1.


In conclusion, CVE-2022-32940 was a critical vulnerability caused by an improper bounds-checking mechanism, which allowed malicious apps to execute arbitrary code with kernel privileges. Although the issue has been fixed in the recent releases of Apple's operating systems, users must remain vigilant and ensure that they have updated their devices to mitigate the risk of exploitation.

Timeline

Published on: 11/01/2022 20:15:00 UTC
Last modified on: 11/02/2022 17:20:00 UTC