Sticky Chat Widget <= 1.4.2 - Unauthenticated SQL Injection

Summary

The Sticky Chat Widget plugin for WordPress is vulnerable to SQL Injection via the 'scw_form_fields' parameter array keys of the 'scw_save_form_data' AJAX action in versions up to, and including, 1.4.2. This is due to the save_form_data() function passing attacker-controlled POST array keys unsanitized to $wpdb->insert(), which wraps column identifiers in backticks without escaping them, allowing a backtick in an attacker-supplied key to break out of the column-identifier list into raw SQL; additionally, the use of filter_input() bypasses WordPress's wp_magic_quotes() protection, and the widget_id validation loop is skipped entirely when no valid widget_id is supplied, leaving $isValid at 1. This makes it possible for unauthenticated attackers to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.