CVE-2024-3628: Cross-Site Scripting (XSS) Vulnerability in EasyEvent WordPress Plugin (Up to 1..)

In this deep-dive, we explore CVE-2024-3628, an exploitable Cross-Site Scripting (XSS) vulnerability in the EasyEvent WordPress plugin (versions up to 1..). This vulnerability could allow privileged users - such as an admin - to execute malicious code in the context of other users via unsanitized input. Notably, the vulnerability is still exploitable even if the WordPress instance has the unfiltered_html permission disallowed.

What is Cross-Site Scripting (XSS)?

Cross-Site Scripting (XSS) is a type of web security vulnerability that allows attackers to inject malicious scripts into otherwise trusted websites or web applications. The injected scripts can be used to steal sensitive information from users, modify the appearance or behavior of the targeted site, or redirect users to malicious websites.

An Overview of the EasyEvent WordPress Plugin

The EasyEvent WordPress plugin is designed to simplify the process of organizing events on WordPress-based websites. Through an intuitive interface, the plugin allows users to create and manage events directly on their site, including event details, tickets, and location information.

Technical Details about the Vulnerability CVE-2024-3628

In the EasyEvent WordPress plugin (versions up to 1..), there are several settings that do not properly sanitize and escape user inputs. As a result, an admin with high privileges could potentially inject malicious scripts through those settings. Additionally, attackers can exploit this vulnerability even when the unfiltered_html permission is disabled in the WordPress instance.

To demonstrate the vulnerability, let's take a look at a code snippet highlighting the insecure code

// File: easyevent-class-admin-page.php
public function save_settings() {
  ...
  $easyevent_options['custom_script'] = esc_textarea( stripslashes( $_POST['easyevent_custom_script'] ) );
  ...
}

In this example, the esc_textarea() function is used to sanitize the easyevent_custom_script input. However, this function is not suitable for safely escaping input in this specific context, allowing the XSS vulnerability to occur.

Exploit Details

Exploiting this vulnerability involves injecting malicious scripts through one or more of the unsafe settings provided by the EasyEvent WordPress plugin. As an example, an attacker could send an HTTP POST request with the following payload to a vulnerable WordPress instance:

POST /wp-admin/options.php HTTP/1.1
...
easyevent_custom_script=alert('XSS');

Timeline

Published on: 05/07/2024 06:15:08 UTC
Last modified on: 05/07/2024 13:39:32 UTC