API Security Hardening
Protect REST APIs against common vulnerabilities with multiple security layers.
Security Middleware Stack (Express)
const helmet = require('helmet');
const rateLimit = require('express-rate-limit');
const mongoSanitize = require('express-mongo-sanitize');
const xss = require('xss-clean');
app.use(helmet());
app.use(mongoSanitize());
app.use(xss());
app.use('/api/', rateLimit({
windowMs: 15 * 60 * 1000,
max: 100
}));
app.use('/api/auth/', rateLimit({
windowMs: 15 * 60 * 1000,
max: 5
}));Input Validation
const { body, validationResult } = require('express-validator');
app.post('/users',
body('email').isEmail().normalizeEmail(),
body('password').isLength({ min: 8 }).matches(/[A-Z]/).matches(/[0-9]/),
body('name').trim().escape().isLength({ max: 100 }),
(req, res) => {
const errors = validationResult(req);
if (!errors.isEmpty()) {
return res.status(400).json({ errors: errors.array() });
}
// Process request
}
);Security Headers
app.use((req, res, next) => {
res.setHeader('Content-Security-Policy', "default-src 'self'");
res.setHeader('X-Frame-Options', 'DENY');
res.setHeader('X-Content-Type-Options', 'nosniff');
res.setHeader('Strict-Transport-Security', 'max-age=31536000; includeSubDomains');
res.setHeader('X-XSS-Protection', '1; mode=block');
next();
});Security Checklist
- HTTPS everywhere
- Authentication on all protected routes
- Input validation and sanitization
- Rate limiting enabled
- Security headers configured
- CORS restricted to allowed origins
- No stack traces in production errors
- Audit logging enabled
- Dependencies regularly updated
Additional Implementations
See references/python-nginx.md for:
- Python FastAPI security middleware
- Pydantic input validation with password rules
- Nginx SSL/TLS and security headers configuration
- HTTP Parameter Pollution prevention
Never Do
- Trust user input without validation
- Return detailed errors in production
- Store secrets in code
- Use GET for state-changing operations
- Disable security for convenience