Reviewing Security

Progress:

• Input Validation & Sanitization
• Authentication & Authorization
• Data Protection
• Infrastructure Security
• Dependencies & Supply Chain
• Error Handling & Logging
• Business Logic Vulnerabilities

1. Input Validation & Sanitization

• SQL injection prevention (parameterized queries)
• XSS protection (output encoding, CSP headers)
• File upload restrictions (type, size, location)
• API input validation schemas
• CSRF tokens on state-changing operations

2. Authentication & Authorization

• Password policies and hashing (bcrypt/Argon2)
• JWT implementation (secure storage, expiration)
• Session management (secure flags, timeout)
• Multi-factor authentication
• Role-based access control (RBAC)
• Principle of least privilege

3. Data Protection

• Encryption at rest and in transit (TLS 1.3+)
• Sensitive data handling (PII, secrets)
• Database security (encrypted connections)
• Backup encryption
• Data retention policies

4. Infrastructure Security

• HTTPS enforcement (HSTS headers)
• Security headers (CSP, X-Frame-Options, etc.)
• Environment variable protection
• Container security (non-root users)
• Network segmentation

5. Dependencies & Supply Chain

• Dependency vulnerability scanning
• Package lock files committed
• Automated security updates
• Third-party service security review

Example 1: Input: Node.js API with user registration Output:

JavaScript
// ❌ VULNERABLE
app.post('/register', (req, res) => {
  const query = `INSERT INTO users (email, password) VALUES ('${req.body.email}', '${req.body.password}')`;
  // Issues: SQL injection, plain text password, no validation
});

// ✅ SECURE
const bcrypt = require('bcrypt');
const { body, validationResult } = require('express-validator');

app.post('/register', [
  body('email').isEmail().normalizeEmail(),
  body('password').isLength({ min: 8 }).matches(/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)/),
], async (req, res) => {
  const errors = validationResult(req);
  if (!errors.isEmpty()) {
    return res.status(400).json({ errors: errors.array() });
  }
  
  const hashedPassword = await bcrypt.hash(req.body.password, 12);
  const query = 'INSERT INTO users (email, password_hash) VALUES (?, ?)';
  // Parameterized query, hashed password, validation
});

Example 2: Input: React component displaying user data Output:

JavaScript
// ❌ VULNERABLE
function UserProfile({ userData }) {
  return <div dangerouslySetInnerHTML={{__html: userData.bio}} />;
  // XSS vulnerability
}

// ✅ SECURE  
import DOMPurify from 'dompurify';

function UserProfile({ userData }) {
  const sanitizedBio = DOMPurify.sanitize(userData.bio);
  return <div dangerouslySetInnerHTML={{__html: sanitizedBio}} />;
  // XSS protection with sanitization
}