CVE-2024-54520: macOS Path Handling Issue Overwrites Arbitrary Files – macOS Sonoma, Sequoia, and Ventura Updates Patch the Vulnerability

The Common Vulnerabilities and Exposures (CVE) Project recently identified CVE-2024-54520, which deals with a path handling issue that could allow attackers to cause certain apps to overwrite arbitrary files. This problem was addressed by Apple with improved validation, and users are advised to update their macOS Sonoma to 14.7.2, macOS Sequoia to 15.2, and macOS Ventura to 13.7.2. In this long read post, we will explore what this issue entails and learn about the exploit in-depth, including its associated risks and how to resolve it.

Code snippet demonstrating vulnerability

Consider the following sample code, where an app attempts to access a file by creating a new URL with a user-provided filename:

import Foundation

func createUrl(for filename: String) -> URL {
    let documentsUrl = FileManager.default.urls(
        for: .documentDirectory,
        in: .userDomainMask
    ).first!
    
    return documentsUrl.appendingPathComponent(filename)
}

let userProvidedFilename = "../../fileToOverwrite.txt"

let fileUrl = createUrl(for: userProvidedFilename)
print("File URL: \(fileUrl)")

In this example, an attacker can easily manipulate 'userProvidedFilename' to include a path traversal attempt by using '../..' in the beginning. This would cause the app to resolve the 'fileUrl' to a location outside of the intended directory, potentially allowing the attacker to overwrite an arbitrary file.

Original references for this CVE can be found on some of the following websites

1. Apple Security Advisory - https://support.apple.com/en-us/HT212804
2. MITRE - https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-54520
3. National Vulnerability Database (NVD) - https://nvd.nist.gov/vuln/detail/CVE-2024-54520

Exploit details

The exploit revolves around the improper handling of file paths by certain apps in macOS operating systems. This could allow attackers to manipulate the paths and cause unintended behavior, such as overwriting arbitrary system files or directories. To exploit this vulnerability, an attacker would need to:

Execute the operation that triggers the app to access or overwrite the target file.

While this exploit may not grant full control of affected systems, it can still significantly impact security and stability.

Solution and mitigation

The primary solution to this vulnerability is updating the affected operating systems to their latest versions, as specified by Apple:

macOS Ventura 13.7.2

Updating macOS can be done through the System Preferences app, under the "Software Update" menu option. Users should also ensure that their apps are up-to-date to further mitigate the risks.

For developers, it's crucial to validate user input and ensure that file paths are properly sanitized to prevent path traversal attempts. For example, using the 'appendingPathComponent' method of 'FileManager' may not be sufficient in certain cases, and additional validation checks should be employed.

In conclusion, CVE-2024-54520 is a significant vulnerability that must be addressed to ensure the security and stability of macOS systems. By understanding the issue, its associated risks, and how to resolve it, both users and developers can implement the necessary measures to protect their data, privacy, and overall system stability. Additionally, always keeping your software up-to-date and vigilantly validating all user-supplied input can go a long way in maintaining the integrity of your system.

Timeline

Published on: 01/27/2025 22:15:13 UTC
Last modified on: 03/03/2025 22:45:38 UTC