Reflected XSS in Simple Basic Contact Form WordPress Plugin

Executive Summary

The Simple Basic Contact Form WordPress plugin version 20250114 or earlier contains a Reflected Cross-Site Scripting (XSS) vulnerability. This happens because the plugin does not properly escape user-supplied input before displaying it back in the contact form output when validation errors occur.

As a result, an unauthenticated attacker can craft a malicious link or form submission that, when visited or submitted by a site visitor, executes malicious JavaScript code in the visitor's browser.

The vulnerability can be exploited by sending POST requests with malicious payloads in form fields such as scf_name, scf_email, or scf_confirm_email, which are reflected without sanitization, enabling JavaScript execution through attributes like autofocus and onfocus.

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Impact Analysis

This vulnerability can allow attackers to execute arbitrary JavaScript code in the browsers of your site visitors without authentication.

Potential impacts include theft of user session cookies, redirection to malicious websites, defacement of the website content, or other malicious actions performed on behalf of the visitor.

Because the attack is reflected and requires the victim to click a crafted link or submit a malicious form, it can be used in phishing or social engineering attacks targeting your users.

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Detection Guidance

This vulnerability can be detected by sending crafted POST requests to the Simple Basic Contact Form plugin with malicious payloads in form fields such as scf_name, scf_email, or scf_confirm_email. If the plugin reflects these inputs without proper escaping, it indicates the presence of the Reflected Cross-Site Scripting vulnerability.

For example, you can use curl commands to test the vulnerability by submitting payloads that include JavaScript event handlers like autofocus or onfocus in these fields and observe if the response reflects the payload unsanitized.

• curl -X POST -d "scf_name=<script>alert(1)</script>&[email protected]&[email protected]" https://targetsite.com/contact-form
• curl -X POST -d "scf_name=test&[email protected]&scf_confirm_email=<img src=x onerror=alert(1)>" https://targetsite.com/contact-form

If the response contains the injected script tags or event handlers without escaping, the vulnerability is present.

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Mitigation Strategies

As there is no known fix available at the time of disclosure, immediate mitigation steps include:

• Disable or deactivate the Simple Basic Contact Form plugin until a patch or update is released.
• Implement Web Application Firewall (WAF) rules to block or sanitize requests containing suspicious payloads targeting the vulnerable form fields.
• Educate site users and administrators to avoid clicking on suspicious links that may exploit this vulnerability.
• Monitor web server logs for unusual POST requests to the contact form that include script tags or event handlers.

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Compliance Impact

The vulnerability is a Reflected Cross-Site Scripting (XSS) issue in the Simple Basic Contact Form WordPress plugin that allows unauthenticated attackers to execute malicious JavaScript in site visitors' browsers. Such vulnerabilities can lead to unauthorized access to user data or session hijacking, which may impact compliance with data protection standards like GDPR and HIPAA by potentially exposing personal or sensitive information.

However, the provided information does not explicitly describe the direct impact of this vulnerability on compliance with specific regulations such as GDPR or HIPAA.

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