Security Documentation

Security Improvements Implemented

This document outlines the security enhancements made to the Credit Scoring with XAI application.

🔐 API Security

1. Input Validation

• Feature Dictionary Size Limit: Maximum 300 features to prevent DoS attacks
• Value Validation: All feature values must be numeric, non-NaN, and non-Infinite
• Type Checking: Strict type validation using Pydantic models
• Empty Input Protection: Prevents empty feature dictionaries

2. Authentication

• API Key Authentication: Optional API key-based authentication via X-API-Key header
• Environment Variable Configuration: API key stored in environment variable API_KEY
• Development Mode: Authentication can be disabled by not setting API_KEY environment variable

Usage:

# Enable authentication
export API_KEY="your-secure-api-key"

# Make authenticated request
curl -X POST http://localhost:8000/predict \
  -H "X-API-Key: your-secure-api-key" \
  -H "Content-Type: application/json" \
  -d '{"features": {...}}'

3. Error Handling

• Generic Error Messages: Clients receive generic error messages
• Detailed Internal Logging: Full error details logged internally for debugging
• Structured Logging: Using Python's logging module with timestamps and levels
• Audit Trail: All predictions logged with relevant metadata (without sensitive data)

4. Security Headers

• CORS Configuration: Configurable allowed origins via ALLOWED_ORIGINS environment variable
• Method Restrictions: Only POST and GET methods allowed
• Credentials Support: Proper CORS credentials handling

🐳 Docker Security

1. Non-Root User

• Dedicated User: Application runs as non-root user appuser (UID 1000)
• File Permissions: All application files owned by appuser
• Privilege Separation: Reduces attack surface and privilege escalation risks

2. Health Checks

• Built-in Health Endpoint: /health endpoint for container orchestration
• Docker Health Check: Automated health monitoring with curl
• Configuration: 30s interval, 10s timeout, 3 retries

3. Minimal Attack Surface

• Slim Base Image: Using Python 3.10-slim to reduce image size
• Minimal Dependencies: Only required system packages installed
• Clean Package Cache: APT cache cleaned to reduce image size

4. Configurable Model Path

• Build Arguments: Model artifact path configurable via Docker build arg
• Environment Variables: Runtime model path configurable via MODEL_PATH

Usage:

# Build with custom model path
docker build --build-arg MODEL_ARTIFACT_PATH=path/to/model -t credit-api .

# Run with environment variables
docker run -e API_KEY="secret" -e MODEL_PATH="/app/model" -p 8000:8000 credit-api

📦 Dependency Management

1. Version Pinning

• All Dependencies Pinned: Version ranges specified for all dependencies
• Regular Updates: Dependencies should be reviewed and updated regularly
• Security Scanning: Use pip-audit or safety to scan for vulnerabilities

Scan for vulnerabilities:

pip install pip-audit
pip-audit -r requirements_serving.txt

2. Separate Requirement Files

• requirements.txt: Training dependencies
• requirements_serving.txt: Production serving dependencies (minimal footprint)

🔍 Monitoring & Logging

1. Structured Logging

• Log Levels: INFO, WARNING, ERROR with appropriate usage
• Timestamps: All logs include timestamps
• Context Information: Logs include relevant context without sensitive data

2. Health Endpoint

• Status Check: /health endpoint returns application status
• Model Validation: Confirms model and explainer are loaded
• Integration: Can be used with monitoring systems (Prometheus, DataDog, etc.)

🛡️ Best Practices for Production

Required Actions Before Production:

1. Enable Authentication

   export API_KEY="$(openssl rand -hex 32)"

2. Configure CORS

   export ALLOWED_ORIGINS="https://yourdomain.com,https://app.yourdomain.com"

3. Use HTTPS/TLS

   • Deploy behind a reverse proxy (nginx, traefik) with TLS
   • Never expose the API directly without HTTPS

4. Rate Limiting

   • Implement rate limiting at reverse proxy level
   • Consider using services like Cloudflare, AWS WAF, or nginx rate limiting

5. Secrets Management

   • Use secrets management systems (AWS Secrets Manager, HashiCorp Vault)
   • Never commit .env files to version control
   • Rotate API keys regularly

6. Monitoring

   • Set up log aggregation (ELK Stack, Splunk, CloudWatch)
   • Monitor for unusual access patterns
   • Set up alerts for failed authentication attempts

7. Regular Security Audits

   • Run dependency vulnerability scans regularly
   • Perform penetration testing
   • Review access logs

8. Data Privacy

   • Ensure GDPR/CCPA compliance for credit data
   • Implement data retention policies
   • Consider data anonymization for logs

Recommended Architecture:

Internet → [Cloudflare/WAF] → [Load Balancer] → [Reverse Proxy with TLS] → [Credit API Container]
                                                          ↓
                                                    [Monitoring & Logging]

📋 Security Checklist

Pre-Production

• Enable API key authentication (API_KEY environment variable set)
• Configure CORS with specific allowed origins
• Set up HTTPS/TLS termination
• Implement rate limiting
• Configure log aggregation and monitoring
• Set up health check monitoring
• Scan dependencies for vulnerabilities
• Review and test error handling
• Document incident response procedures

Production Maintenance

• Regular dependency updates and vulnerability scans
• Log review and analysis (weekly/monthly)
• API key rotation (quarterly)
• Security audit (annually)
• Backup and disaster recovery testing
• Performance and capacity monitoring
• Compliance reviews (GDPR, PCI-DSS if applicable)

🚨 Known Limitations

1. No Built-in Rate Limiting: Must be implemented at reverse proxy level
2. Simple API Key Auth: Consider upgrading to OAuth2/JWT for production
3. No Request Size Limit: Should be configured at reverse proxy level
4. No Model Versioning: Consider implementing model version tracking
5. No Adversarial Attack Detection: Consider adding input anomaly detection

📚 Additional Resources

• OWASP API Security Top 10
• FastAPI Security Documentation
• Docker Security Best Practices
• NIST Cybersecurity Framework

🔄 Security Updates

This document should be reviewed and updated whenever:

• New security features are added
• Vulnerabilities are discovered and fixed
• Production deployment architecture changes
• Compliance requirements change

---

Last Updated: 2024 Version: 1.0