Executive Summary

This vulnerability affects the Eventin – Event Manager, Events Calendar, Event Tickets and Registrations WordPress plugin (also known as WP Event Solution). It occurs because the plugin lacks proper capability checks on the 'post_settings' function, allowing unauthenticated attackers to modify plugin settings. Additionally, insufficient input sanitization and output escaping on the 'etn_primary_color' setting enable attackers to inject arbitrary web scripts (Cross-Site Scripting or XSS) that execute when users load pages with Eventin styles. The vulnerability allows unauthorized modification of data and potential execution of malicious scripts. [1, 4]

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Impact Analysis

This vulnerability can impact you by allowing unauthenticated attackers to change plugin settings without permission, potentially disrupting your website's functionality or appearance. More critically, attackers can inject malicious scripts via the color settings, which execute in the browsers of users visiting pages where the plugin's styles are loaded. This can lead to theft of user data, session hijacking, or other malicious activities performed through Cross-Site Scripting (XSS) attacks. [1, 4]

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Detection Guidance

To detect this vulnerability, monitor for unauthorized or unauthenticated REST API requests attempting to modify plugin settings, especially those targeting the 'post_settings' function or the settings endpoint of the WP Event Solution plugin. Look for requests missing the required 'X-WP-Nonce' header or requests that modify color settings such as 'etn_primary_color' or 'etn_secondary_color'. You can use network monitoring tools or web server logs to identify suspicious POST requests to the plugin's API endpoints. Example commands include using curl to test API access without nonce: curl -X POST https://yourwordpresssite.com/wp-json/wp-event-solution/v1/settings -d '{"etn_primary_color":"#000000"}' -H "Content-Type: application/json" and checking if the request is accepted. Also, use grep or similar tools on server logs to find unauthorized access attempts. Additionally, scanning for plugin versions up to 4.0.51 can help identify vulnerable installations. [2, 4]

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Mitigation Strategies

Immediate mitigation steps include: 1. Update the WP Event Solution plugin to a version later than 4.0.51 where the vulnerability is patched. 2. Ensure that REST API requests modifying plugin settings require a valid 'X-WP-Nonce' header and that user capabilities such as 'manage_options' are properly enforced. 3. Apply or verify that input sanitization functions like 'sanitize_hex_color()' are used for color settings to prevent XSS attacks. 4. Restrict access to the plugin's REST API endpoints to authenticated and authorized users only. 5. Monitor logs for suspicious API requests and block unauthorized attempts. These steps will prevent unauthorized modification of plugin settings and mitigate XSS risks. [1, 2, 4]

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