Fix Broken User Authentication in Polka

Polka's minimalist footprint is a feature, but it's a security nightmare when developers roll their own auth logic. Broken authentication in Polka apps typically manifests as insecure session management, lack of cookie signing, and missing security flags. If you aren't cryptographically binding your sessions and enforcing transport security, you're just handing over admin access to anyone with a browser console.

The Vulnerable Pattern

const polka = require('polka');
polka()
.get(‘/admin’, (req, res) => {
// VULNERABILITY: Raw header parsing and predictable cookie values
const cookie = req.headers.cookie;
if (cookie && cookie.includes(‘user=admin’)) {
res.end(‘Sensitive Admin Dashboard’);
} else {
res.statusCode = 401;
res.end(‘Unauthorized’);
}
})
.listen(3000);

The Secure Implementation

The vulnerable code relies on client-controlled plaintext strings within the 'Cookie' header, which are trivial to spoof. The secure implementation replaces this with 'express-session' for server-side state management. Key hardening includes: 1. Cryptographic signing of session IDs using a strong secret. 2. Setting the 'httpOnly' flag to block JavaScript access to the session token. 3. Setting the 'secure' flag to ensure tokens never travel over unencrypted channels. 4. Implementing 'sameSite: strict' to neutralize CSRF vectors. Don't trust the client; verify the session server-side.

const polka = require('polka');
const session = require('express-session');
const RedisStore = require('connect-redis')(session);
polka()
.use(session({
secret: process.env.SESSION_SECRET, // High-entropy secret from env
resave: false,
saveUninitialized: false,
name: ‘__Host-session_id’,
cookie: {
httpOnly: true,   // Prevents XSS-based session theft
secure: true,     // Enforces HTTPS
sameSite: ‘strict’, // Mitigates CSRF
maxAge: 3600000   // 1 hour expiry
}
}))
.get(‘/admin’, (req, res) => {
if (req.session && req.session.isAdmin) {
res.end(‘Secure Admin Dashboard’);
} else {
res.statusCode = 403;
res.end(‘Forbidden’);
}
})
.listen(3000);