How to remediate – Contact Form 7 Style Plugin for WordPress Cross-Site Request F…

1. Introduction

The Contact Form 7 Style Plugin for WordPress is affected by a Cross-Site Request Forgery (CSRF) vulnerability. This allows an attacker to perform actions on behalf of an authenticated user without their knowledge, potentially leading to unintended changes or data manipulation. Systems running vulnerable versions of the plugin are at risk. A successful exploit could compromise the integrity of website data and functionality.

2. Technical Explanation

The vulnerability stems from missing CSRF protection in the Contact Form 7 Style Plugin for WordPress. An attacker can craft a malicious request that, when triggered (e.g., through a phishing link), forces an authenticated user to perform actions on the website without their consent. The scanner relied only on self-reported version numbers and has not tested these issues directly.

• Root cause: Lack of CSRF tokens or inadequate validation in form submission handling.
• Exploit mechanism: An attacker crafts a malicious HTML page containing a request to the vulnerable endpoint, embedding it within an image tag or iframe. When a logged-in user visits this page, their browser automatically submits the request with their authentication cookies.
• Scope: WordPress websites using Contact Form 7 Style Plugin for WordPress.

3. Detection and Assessment

Confirming vulnerability involves checking the installed plugin version and reviewing its configuration.

• Quick checks: Check the plugin version in the WordPress admin panel under ‘Plugins’ > ‘Installed Plugins’.
• Scanning: Wordfence reports this vulnerability with signature ID 12345678 (example only).
• Logs and evidence: Review web server access logs for unusual POST requests originating from external sources.

wp plugin list | grep contact-form-7-style

4. Solution / Remediation Steps

Remove the vulnerable plugin to mitigate the risk.

4.1 Preparation

• No services need to be stopped. A roll back plan is to re-install the plugin from a backup if needed.
• Change windows are not required, but it’s good practice to inform stakeholders of planned maintenance.

4.2 Implementation

1. Step 1: Log in to your WordPress admin panel.
2. Step 2: Navigate to ‘Plugins’ > ‘Installed Plugins’.
3. Step 3: Locate the ‘Contact Form 7 Style Plugin for WordPress’ plugin.
4. Step 4: Click ‘Deactivate’ and then ‘Delete’.

4.3 Config or Code Example

No configuration changes are needed; the solution is to remove the plugin.

Before

Contact Form 7 Style Plugin for WordPress - Active

After

Contact Form 7 Style Plugin for WordPress - Not Installed

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent CSRF vulnerabilities.

• Least privilege: Ensure users have only the necessary permissions to perform their tasks, limiting potential damage from a successful exploit.
• Input validation: Validate all user inputs to prevent malicious data from being processed.

4.5 Automation (Optional)

Automating plugin removal is possible using WP-CLI.

wp plugin deactivate contact-form-7-style --network && wp plugin delete contact-form-7-style --network

5. Verification / Validation

Confirm the fix by verifying that the plugin is no longer installed and checking for CSRF tokens on form submission endpoints.

• Post-fix check: Run `wp plugin list` and confirm ‘contact-form-7-style’ is not listed.
• Re-test: Repeat the quick checks from section 3 to ensure the vulnerability is no longer present.
• Smoke test: Verify that other contact forms on your website are still functioning correctly.
• Monitoring: Monitor web server logs for any suspicious activity related to form submissions.

wp plugin list | grep contact-form-7-style

6. Preventive Measures and Monitoring

Regularly update plugins, use security scanners, and implement a robust patch management process.

• Baselines: Update your WordPress security baseline to include regular plugin updates.
• Pipelines: Integrate vulnerability scanning into your CI/CD pipeline.
• Asset and patch process: Establish a monthly or quarterly schedule for reviewing and applying plugin updates.

7. Risks, Side Effects, and Roll Back

Removing the plugin may affect website styling if it was used for form presentation.

• Risk or side effect 1: Website styling changes if the plugin provided custom CSS. Mitigation: Restore from backup or find an alternative styling solution.
• Roll back: Re-install the ‘Contact Form 7 Style Plugin for WordPress’ from a previous backup.

8. References and Resources

• Vendor advisory or bulletin: https://wordpress.org/plugins/contact-form-7-style/
• NVD or CVE entry: CVE-2021-24159
• Product or platform documentation relevant to the fix: https://www.wordfence.com/blog/2021/02/unpatched-vulnerability-50000-wp-sites-must-find-alternative-for-contact-form-7-style/