The Ultimate PHP Security Checklist of WordPress Best Practices

Introduction

PHP is the backbone of WordPress, powering its functionality and dynamic content. Ensuring the security of your WordPress site’s PHP environment is critical to protect it from vulnerabilities, malicious attacks, and performance issues. This checklist provides essential best practices for securing PHP and your WordPress site.

Why PHP Security Matters for WordPress

Key Reasons:

1. Prevent Exploits: Secure PHP configurations reduce vulnerabilities like SQL injections and remote code execution.
2. Enhance Performance: A secure PHP setup minimizes server overload and downtime.
3. Safeguard Data: Protect sensitive user information from unauthorized access.

PHP Security Checklist for WordPress

1. Keep PHP Updated

An outdated PHP version is a significant security risk.

Steps to Update PHP:

1. Check your current PHP version under Tools > Site Health in WordPress.
2. Contact your hosting provider to enable the latest stable PHP version.
3. Test your site for compatibility after the update using tools like PHP Compatibility Checker.

2. Disable Error Reporting

Displaying errors publicly can expose sensitive information about your site’s configuration.

How to Disable:

1. Edit the wp-config.php file.
2. Add or modify the following line:

define('WP_DEBUG', false);
define('WP_DEBUG_DISPLAY', false);

3. Restrict PHP Execution

Prevent unauthorized execution of PHP files in sensitive directories like wp-content/uploads.

Steps:

1. Create an .htaccess file in the uploads directory.
2. Add the following code:

<Files *.php>
    deny from all
</Files>

4. Harden File Permissions

Restrict file and folder permissions to prevent unauthorized access or modifications.

Recommended Permissions:

• Files: 644
• Directories: 755
• wp-config.php: 600

How to Apply:

Use an FTP client or hosting control panel to adjust permissions.

5. Limit PHP Functions

Disable potentially dangerous PHP functions that attackers often exploit.

Example:

1. Edit the php.ini file.
2. Add the following line:

disable_functions = exec,passthru,shell_exec,system,proc_open,popen,curl_exec,curl_multi_exec,parse_ini_file,show_source

6. Use a Web Application Firewall (WAF)

A WAF filters malicious traffic before it reaches your PHP environment.

Recommended Tools:

• Cloudflare (Free and Paid Plans)
• Sucuri Firewall

7. Enable HTTPS and SSL

Encrypt communication between your server and users.

Steps:

1. Obtain an SSL certificate from your hosting provider or Let’s Encrypt.
2. Force HTTPS by adding the following to .htaccess:

RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]

Advanced PHP Security Configurations

1. Implement Security Headers

Add HTTP security headers to prevent common attacks like XSS and clickjacking.

Example:

Add the following to .htaccess:

Header set X-Content-Type-Options "nosniff"
Header set X-Frame-Options "DENY"
Header set Content-Security-Policy "default-src 'self';"

2. Use Open_basedir Restriction

Restrict PHP scripts to specific directories.

Steps:

1. Edit the php.ini file.
2. Add the following line:

open_basedir = /var/www/html:/tmp/

3. Monitor PHP Logs

Regularly review PHP error logs for suspicious activity or errors.

Location:

• Check your hosting control panel for log locations.
• Alternatively, access the logs via FTP in the /var/log directory.

4. Set Up Fail2Ban for Brute Force Protection

Fail2Ban blocks IPs with suspicious login attempts.

Steps:

1. Install Fail2Ban on your server.
2. Configure WordPress-specific rules in /etc/fail2ban/jail.local.

Monitoring and Maintenance

1. Use Security Plugins

Install WordPress security plugins for real-time monitoring and alerts.

Recommended Plugins:

• Wordfence Security
• iThemes Security
• Sucuri Security

2. Schedule Regular Security Audits

Audit your PHP and WordPress setup monthly to detect vulnerabilities.

3. Back Up Regularly

Use plugins like UpdraftPlus or BackupBuddy to create backups before implementing changes.

Troubleshooting Common PHP Security Issues

1. “Outdated PHP Version”

• Cause: Incompatible plugins or themes.
• Solution: Update all plugins/themes before upgrading PHP.

2. “PHP Errors Displayed on Site”

• Cause: Debugging enabled in production.
• Solution: Disable WP_DEBUG in wp-config.php.

3. “Unauthorized Access to Sensitive Files”

• Cause: Incorrect file permissions.
• Solution: Adjust permissions as outlined above.

Recommended Tools for PHP Security

1. Cloudflare: Protects against DDoS and malicious traffic.
2. Sucuri Firewall: Advanced web application firewall.
3. PHP Compatibility Checker: Tests compatibility with newer PHP versions.
4. Fail2Ban: Blocks suspicious IP addresses.

Conclusion

Securing PHP in WordPress is crucial for maintaining a safe and robust website. By following this checklist, you can harden your PHP environment, protect sensitive data, and ensure your site runs smoothly. Regular updates, monitoring, and proactive measures will keep your WordPress site resilient against evolving threats.