OWASP Top 10
Common Vulnerabilities
SQL Injection
- Vulnerable: String concatenation in queries
- Fix: Parameterized queries (PreparedStatement)
XSS
- Stored, Reflected, DOM-based
- Fix: Sanitize input, encode output, CSP headers
CSRF
- Fix: CSRF tokens, SameSite cookies
OWASP Top 10
- Broken Access Control
- Cryptographic Failures
- Injection
- Insecure Design
- Security Misconfiguration
- Vulnerable Components
- Auth Failures
- Data Integrity Failures
- Logging Failures
- SSRF
Defense in Depth
Security Layers
- Network: Firewall, VPC
- Transport: TLS 1.3, HSTS
- Application: Input validation, CSRF
- Authentication: MFA, JWT, rate limiting
- Authorization: RBAC, deny by default
- Data: Encryption, tokenization
- Monitoring: Logging, alerting
Secrets Management
- Never commit to code
- Use env vars or secret managers
- Rotate regularly
Key Points
- Understanding Security Questions is essential for production systems
- Always consider scalability and maintainability
- Test thoroughly before deploying to production
- Monitor performance and set up alerting
Common Patterns
- Validation: Always validate input at the boundary
- Error Handling: Use structured error responses
- Logging: Log key events for debugging
- Testing: Unit, integration, and load tests
- Documentation: Keep docs updated with code changes
Practice Problems
Design and implement a solution for Security Questions in a backend system. Consider scalability, error handling, and production readiness.
Solution
// Security Questions implementation
// Key aspects: validation, error handling, logging, testing
public class SecurityQuestions {
// Production-ready implementation
}Identify and handle edge cases for Security Questions. What happens under high load, with invalid input, or during failures?
Solution
// Edge case handling:
// 1. Null/empty input -> validation
// 2. High load -> rate limiting, queuing
// 3. Failures -> retries, circuit breaker
// 4. Concurrent access -> locks, idempotencyWrite a testing strategy for Security Questions. Include unit tests, integration tests, and performance tests.
Solution
// Test plan:
// - Unit: 80% coverage target
// - Integration: API contracts
// - Performance: latency, throughput
// - Chaos: failure injectionQuiz
1. How to prevent SQL injection?
2. CSRF tokens purpose?
3. What is the primary purpose of Security Questions?
4. What is a common mistake when implementing Security Questions?
Flashcards
Question
Prevent SQL injection?
Click to reveal answer
Answer
Use parameterized queries (PreparedStatement)
Question
Prevent CSRF?
Click to reveal answer
Answer
CSRF tokens + SameSite cookies
Question
What is Security Questions?
Click to reveal answer
Answer
Security Questions is a key concept in backend development.
Question
When to use Security Questions?
Click to reveal answer
Answer
Use Security Questions when building production systems that require reliability, scalability, and maintainability.
Question
Security Questions best practices
Click to reveal answer
Answer
Follow SOLID principles, write clean code, test thoroughly, document decisions, and monitor in production.
Revision Notes
Key Takeaways
- 1.SQL injection: parameterized queries
- 2.XSS: sanitize + encode + CSP
- 3.CSRF: tokens + SameSite cookies
- 4.Defense in depth: multiple layers
Interview Tips
- •Explain each OWASP Top 10
- •Show fixes in code
- •Discuss security vs performance tradeoffs
Cheat Sheet
Security Interview
- SQL Injection: Parameterized queries
- XSS: Input sanitize + Output encode + CSP
- CSRF: Tokens + SameSite cookies
- Defense in Depth: Multiple security layers