secure-headers

Secure HTTP Headers

Configure HTTP security headers to protect against common web attacks.

When to Use

• Setting up a new web application
• Hardening existing applications
• Fixing security scanner findings
• Implementing Content Security Policy
• Preventing clickjacking

Essential Security Headers

Header	Purpose	Priority
Content-Security-Policy	XSS prevention	HIGH
Strict-Transport-Security	Force HTTPS	HIGH
X-Frame-Options	Clickjacking	HIGH
X-Content-Type-Options	MIME sniffing	MEDIUM
Referrer-Policy	Privacy	MEDIUM
Permissions-Policy	Feature control	MEDIUM

Implementation

Express.js with Helmet

const helmet = require('helmet');

app.use(helmet({
  // Content Security Policy
  contentSecurityPolicy: {
    directives: {
      defaultSrc: ["'self'"],
      scriptSrc: ["'self'", "https://cdn.example.com"],
      styleSrc: ["'self'", "'unsafe-inline'"],  // Consider removing unsafe-inline
      imgSrc: ["'self'", "data:", "https:"],
      connectSrc: ["'self'", "https://api.example.com"],
      fontSrc: ["'self'", "https://fonts.gstatic.com"],
      objectSrc: ["'none'"],
      mediaSrc: ["'self'"],
      frameSrc: ["'none'"],
      frameAncestors: ["'none'"],
      formAction: ["'self'"],
      baseUri: ["'self'"],
      upgradeInsecureRequests: []
    }
  },

  // HTTP Strict Transport Security
  hsts: {
    maxAge: 31536000,  // 1 year
    includeSubDomains: true,
    preload: true
  },

  // Prevent clickjacking
  frameguard: { action: 'deny' },

  // Prevent MIME type sniffing
  noSniff: true,

  // Referrer Policy
  referrerPolicy: { policy: 'strict-origin-when-cross-origin' },

  // Permissions Policy
  permittedCrossDomainPolicies: { permittedPolicies: 'none' }
}));

// Additional headers
app.use((req, res, next) => {
  // Permissions Policy (formerly Feature-Policy)
  res.setHeader('Permissions-Policy',
    'geolocation=(), microphone=(), camera=(), payment=()');

  // Cross-Origin policies
  res.setHeader('Cross-Origin-Embedder-Policy', 'require-corp');
  res.setHeader('Cross-Origin-Opener-Policy', 'same-origin');
  res.setHeader('Cross-Origin-Resource-Policy', 'same-origin');

  next();
});