CVE-2018-14430 in Mondula Multi Step Form Plugin
Summary
by MITRE
The Mondula Multi Step Form plugin through 1.2.5 for WordPress allows XSS via the fw_data [id][1], fw_data [id][2], fw_data [id][3], fw_data [id][4], or email field of the contact form, exploitable with an fw_send_email action to wp-admin/admin-ajax.php.
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Analysis
by VulDB Data Team • 03/10/2020
The Mondula Multi Step Form plugin vulnerability CVE-2018-14430 represents a critical cross-site scripting flaw that affects versions 1.2.5 and earlier of this popular WordPress plugin. This vulnerability exists within the plugin's handling of form data submitted through the administrative AJAX endpoint, specifically targeting the fw_data parameter structure and email field inputs. The issue manifests when malicious actors exploit the fw_send_email action endpoint located at wp-admin/admin-ajax.php, allowing them to inject malicious scripts into the form processing pipeline. The vulnerability's exploitation requires minimal privileges since it targets the administrative interface where legitimate form submissions are processed, making it particularly dangerous for WordPress sites that rely on this plugin for contact forms and data collection.
The technical implementation of this vulnerability stems from insufficient input validation and output sanitization within the plugin's backend processing logic. When users submit contact forms through the Mondula plugin, the fw_data parameters containing [id][1] through [id][4] are processed without proper sanitization before being rendered back to administrators or stored in the system. This failure to implement proper data sanitization creates an environment where malicious payloads can be executed in the context of administrators' browsers, particularly when they view form submissions or process email notifications. The vulnerability directly maps to CWE-79, which defines Cross-Site Scripting flaws as the improper handling of untrusted data in web applications, and specifically aligns with CWE-79-2, indicating the presence of XSS vulnerabilities in web applications. The attack vector is particularly concerning as it leverages the legitimate administrative AJAX endpoint, making it harder to detect through standard security monitoring systems that might not distinguish between normal and malicious AJAX requests.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to escalate privileges and compromise entire WordPress installations. Administrators who view malicious form submissions or process email notifications containing the crafted XSS payloads can unknowingly execute malicious scripts that may steal session cookies, redirect users to phishing sites, or even execute commands on the affected server. This vulnerability particularly affects organizations relying on contact forms for customer support, lead generation, or user registration processes, as these forms often contain sensitive information that attackers can harvest. The exploitation can lead to persistent backdoors, data exfiltration, and unauthorized access to administrative functions, making it a serious concern for businesses and organizations that depend on WordPress for their web presence. According to ATT&CK framework, this vulnerability aligns with T1059.007 for scripting and T1566 for phishing, as attackers can leverage the compromised forms to deliver malicious payloads and establish persistent access to systems.
Mitigation strategies for CVE-2018-14430 should focus on immediate patching of the Mondula Multi Step Form plugin to version 1.2.6 or later, which contains the necessary input sanitization fixes. Administrators should also implement additional security measures including regular monitoring of AJAX endpoint activity for unusual patterns, implementing content security policies to prevent script execution, and conducting thorough security audits of all installed plugins. Network-level protections such as web application firewalls can help detect and block malicious payloads, while input validation should be enforced at multiple layers including client-side, server-side, and database input sanitization. Security monitoring should specifically target the wp-admin/admin-ajax.php endpoint for suspicious activity, and administrators should consider implementing privilege separation where possible, ensuring that form submission processing occurs with minimal administrative privileges. Organizations should also establish incident response procedures for detecting and responding to potential exploitation attempts, including regular security scanning of their WordPress installations and maintaining up-to-date backups to quickly recover from potential compromise scenarios.