Web Security Basics

Importance of Web Security

Web security protects users and applications from malicious attacks. Understanding common vulnerabilities is crucial for developers to build secure systems.

HTTPS and SSL/TLS

HTTPS encrypts data in transit between client and server. Use free certificates from Let's Encrypt and redirect HTTP to HTTPS.

Cross-Site Scripting (XSS)

XSS attacks inject malicious scripts into web pages viewed by other users. Prevent with input validation and output encoding:

• Escape HTML entities (< to &lt;)
• Use Content Security Policy (CSP) headers
• Sanitize user input with libraries like DOMPurify

Cross-Site Request Forgery (CSRF)

CSRF tricks users into performing unwanted actions. Protect with:

• CSRF tokens in forms
• SameSite cookie attribute
• Check Origin and Referer headers

Authentication Best Practices

• Use secure password hashing (bcrypt, Argon2)
• Implement multi-factor authentication (MFA)
• Use HTTP-only, secure, SameSite cookies
• Implement session management with expiration
• Avoid storing sensitive data in JWT payloads

SQL Injection Prevention

SQL injection occurs when malicious SQL is inserted into queries. Use parameterized queries or ORM libraries:

// Bad
  const query = "SELECT * FROM users WHERE id = " + userId;

  // Good
  const query = "SELECT * FROM users WHERE id = ?";
  db.query(query, [userId]);

Other Vulnerabilities

• Clickjacking: Prevent with X-Frame-Options headers
• Security Misconfigurations: Disable directory listing, remove default credentials
• Insecure Direct Object References: Use UUIDs instead of sequential IDs

Security Headers

Use HTTP security headers:

• X-Content-Type-Options: nosniff
• X-XSS-Protection: 1; mode=block
• Strict-Transport-Security: max-age=31536000

Security Tools

• OWASP ZAP: Web application scanner
• Burp Suite: Intercepting proxy for testing
• Snyk: Vulnerability scanning for dependencies

Security is an ongoing process. Stay updated with latest threats and regularly audit your applications.