Payment Website Security Checklist

TL;DR

This guide helps you assess and improve the security of your payment website to protect customer data and prevent fraud. It covers key areas like PCI DSS compliance, vulnerability scanning, strong passwords, secure coding practices, monitoring, and incident response.

1. Understand PCI DSS Requirements

If you handle credit card information, you must comply with the Payment Card Industry Data Security Standard (PCI DSS). This is non-negotiable. The level of compliance depends on how you process payments (directly or via a third party).

• Self-Assessment Questionnaire (SAQ): Determine which SAQ version applies to your business.
• Qualified Security Assessor (QSA): For higher levels of processing, you’ll need a QSA to audit your systems.
• PCI DSS Documentation: Familiarise yourself with the official PCI DSS documentation.

2. Vulnerability Scanning & Penetration Testing

Regularly scan your website for vulnerabilities and, ideally, conduct penetration testing.

1. Vulnerability Scanner: Use a reputable vulnerability scanner (e.g., Nessus, OpenVAS, Qualys) to identify weaknesses in your code and infrastructure. Scan at least quarterly, or after any significant changes.
2. Penetration Testing: Hire ethical hackers to simulate real-world attacks on your website. Do this annually, or more frequently if you’re high risk.
3. Remediation: Fix all identified vulnerabilities promptly. Prioritise critical and high-severity issues.

3. Strong Passwords & Access Control

Weak passwords are a major security risk.

• Password Policy: Enforce strong password requirements (minimum length, complexity, regular changes).
• Multi-Factor Authentication (MFA): Implement MFA for all administrative accounts. This adds an extra layer of security beyond just a password.
• Least Privilege: Grant users only the minimum access they need to perform their jobs.
• Regular Reviews: Regularly review user accounts and permissions. Remove inactive or unnecessary accounts.

4. Secure Coding Practices

Poorly written code can introduce vulnerabilities.

1. Input Validation: Validate all user input to prevent injection attacks (SQL injection, cross-site scripting).
2. Output Encoding: Encode output data to protect against XSS attacks.
3. Secure Libraries: Use secure and up-to-date libraries and frameworks.
4. Code Reviews: Conduct regular code reviews to identify potential security flaws.

// Example of input validation in PHP

$username = htmlspecialchars($_POST['username']); // Prevent XSS

5. SSL/TLS Certificates

Ensure your website uses a valid and up-to-date SSL/TLS certificate.

• HTTPS: All pages that handle sensitive data (login, checkout) must be served over HTTPS.
• Certificate Authority: Obtain a certificate from a trusted Certificate Authority (CA).
• Automatic Renewal: Configure automatic renewal of your SSL/TLS certificate to avoid expiry issues.

6. Monitoring & Logging

Monitor your website for suspicious activity and log all important events.

• Intrusion Detection System (IDS): Implement an IDS to detect malicious traffic.
• Web Application Firewall (WAF): Use a WAF to protect against common web attacks.
• Log Analysis: Regularly review logs for unusual patterns or errors.

7. Incident Response Plan

Have a plan in place for responding to security incidents.

• Incident Reporting: Establish clear procedures for reporting security incidents.
• Containment: Isolate affected systems to prevent further damage.
• Eradication: Remove the cause of the incident.
• Recovery: Restore systems and data from backups.
• Post-Incident Analysis: Learn from incidents and improve your security measures.

8. Third-Party Payment Processors

If you use a third-party payment processor, ensure they are PCI DSS compliant.

• Due Diligence: Research the processor’s security practices and compliance status.
• Tokenization: Use tokenization to protect sensitive card data. The processor handles the actual card details.
• Regular Audits: Request regular audits of the processor’s security controls.