Secure Solution Development Guide

TL;DR

This guide outlines key steps for building secure solutions from the start. It covers planning, coding practices, testing, and deployment to minimise vulnerabilities.

1. Planning & Threat Modelling

1. Define Security Requirements: What data are you protecting? What regulations apply (e.g., GDPR)? Document these clearly.
2. Threat Modelling: Identify potential attackers and how they might try to compromise your system. Use frameworks like STRIDE:
   • Spoofing
   • Tampering
   • Repudiation
   • Information Disclosure
   • Denial of Service
   • Elevation of Privilege
3. Data Flow Diagrams: Map how data moves through your system. This helps pinpoint sensitive areas.
4. Risk Assessment: Evaluate the likelihood and impact of each threat. Prioritise mitigation efforts based on risk level.

2. Secure Coding Practices

1. Input Validation: Always validate user input before using it. This prevents injection attacks (SQL, XSS, etc.). Example (Python):

   def process_input(user_data):
       if not user_data.isalnum():
           return "Invalid Input!"
       else:
           # Process the validated input
           return "Input processed successfully"
   

2. Output Encoding: Encode data before displaying it to users, especially if it contains user-supplied content. This prevents XSS.
3. Authentication & Authorisation: Use strong authentication methods (multi-factor where possible). Implement role-based access control (RBAC).
4. Session Management: Securely manage sessions. Use secure cookies (HttpOnly, Secure flags) and appropriate session timeouts.
5. Cryptography: Use well-established cryptographic libraries. Avoid implementing your own crypto algorithms. Example (generating a random salt):

   import secrets
   salt = secrets.token_hex(16)
   

6. Error Handling: Handle errors gracefully and avoid revealing sensitive information in error messages.
7. Code Reviews: Have your code reviewed by peers to identify potential vulnerabilities.

3. Testing

1. Static Analysis Security Testing (SAST): Use tools to scan your source code for vulnerabilities without running the application.
2. Dynamic Application Security Testing (DAST): Test your running application for vulnerabilities by simulating attacks.
3. Penetration Testing: Hire ethical hackers to attempt to compromise your system. This provides a real-world assessment of security.
4. Fuzzing: Provide invalid, unexpected, or random data as input to identify crashes and potential vulnerabilities.
5. Unit Tests: Write unit tests that specifically target security concerns (e.g., input validation).

4. Deployment & Monitoring

1. Secure Configuration: Follow secure configuration guidelines for your servers, databases, and other infrastructure components.
2. Regular Updates: Keep all software up to date with the latest security patches.
3. Web Application Firewall (WAF): Use a WAF to protect against common web attacks.
4. Intrusion Detection/Prevention Systems (IDS/IPS): Monitor your network for malicious activity.
5. Logging & Auditing: Log all security-relevant events and regularly review logs. Ensure adequate audit trails are in place.
6. Vulnerability Scanning: Regularly scan your deployed systems for vulnerabilities.

5. Cyber Security Considerations

Remember that cyber security is an ongoing process, not a one-time fix.

• Principle of Least Privilege: Grant users only the minimum necessary permissions to perform their tasks.
• Defence in Depth: Implement multiple layers of security controls. If one layer fails, others should provide protection.
• Incident Response Plan: Have a plan in place for responding to security incidents.