How to Fix Broken Authentication Vulnerabilities

In this tutorial, you'll learn about How to Fix Broken Authentication Vulnerabilities. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

Broken authentication vulnerabilities occur when session tokens are predictable, session IDs are exposed in URLs, passwords are stored unsafely, or login endpoints lack Rate Limiting, allowing attackers to hijack sessions or brute-force credentials.

Quick Fix

Wrong

std::string sessionId = std::to_string(userId);  // predictable!

response.setCookie("session", sessionId);

An attacker can guess or enumerate session IDs by incrementing the user ID.

Right

std::string sessionId = generateSecureToken(32);
// Store in server-side session store
sessionStore[sessionId] = Session{userId, expiry};
response.setCookie("session", sessionId, {
    .httpOnly = true,
    .secure = true,
    .sameSite = "Strict"
});

Fix for password storage

// Wrong: plaintext or MD5
std::string hash = md5(password);

// Right: bcrypt with cost factor
std::string hash = bcrypt::hash(password, 12);

Fix for login Rate Limiting

app.post("/login", [](Request& req, Response& res) {
    std::string ip = req.clientIP();
    int attempts = loginAttempts[ip]++;
    if (attempts > 5) {
        res.status(429).send("Too many attempts. Try again in 5 minutes.");
        return;
    }
    // verify credentials...
});

Fix for session fixation

app.post("/login", [](Request& req, Response& res) {
    if (verifyCredentials(req)) {
        // Regenerate session ID after login
        auto oldSession = req.sessionId;
        req.sessionId = generateSecureToken(32);
        sessionStore.remove(oldSession);
    }
});

Prevention

• Use framework-provided session management (do not roll your own).
• Store passwords with bcrypt, scrypt, or Argon2.
• Use HTTP-only, Secure, SameSite cookies.
• Implement Rate Limiting on login, registration, and password reset.
• Regenerate session IDs after login and privilege escalation.

DodaTech Tools

Doda Browser's authentication audit checks for weak session management, password storage, and Rate Limiting. DodaZIP encrypts and archives session audit logs. Durga Antivirus Pro detects brute-force login attacks in real time.

Common Mistakes with authentication

1. Forgetting that lazy evaluation defers computation until the value is forced, causing space leaks with unevaluated thunks
2. Using return to exit a function early instead of wrapping a pure value in the monad
3. Mixing let bindings with <- bindings in do notation, producing type errors

These mistakes appear frequently in real-world BROKEN code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ