Credential Stuffing in Sails with Basic Auth

Credential stuffing in a Sails application that relies on HTTP Basic Auth occurs when an attacker uses previously breached username and password pairs to sign in. Because Basic Auth transmits credentials in an easily extractable format encoded in the Authorization header, reused credentials can be replayed directly to authenticate without triggering more sophisticated, behavior-based protections. Sails does not inherently enforce account lockout, one-time tokens, or rate limits on authentication endpoints, so automated scripts can iterate through credential lists rapidly.

In a typical Sails setup, controllers may parse the Authorization header manually or with a helper. If the implementation only validates the presence of credentials and does not incorporate multi-factor checks, anomaly detection, or adaptive throttling, each request appears valid as long as the credentials match. Attackers often target these endpoints because they are unauthenticated attack surfaces and, with Basic Auth, the credentials themselves are presented with each request, simplifying automation. The risk is compounded when the same credentials are used across multiple services, a common habit that fuels the effectiveness of stuffing campaigns.

Because middleBrick scans unauthenticated attack surfaces and tests authentication mechanisms, it can identify endpoints that accept Basic Auth without additional protections. Findings may highlight missing rate limiting, weak password policies, and the absence of suspicious activity detection, all of which are critical when defending against credential stuffing. The scanner does not fix these issues but provides prioritized findings with remediation guidance to help developers strengthen authentication logic and reduce exposure.

To mitigate credential stuffing in Sails, move away from relying solely on HTTP Basic Auth for sensitive operations. When Basic Auth must be used, enforce strict transport security and augment it with additional controls. Below are concrete remediation steps and code examples that reduce risk by combining transport protection, rate control, and server-side validation.

First, always serve your application over HTTPS to prevent credential interception. Then, avoid using Basic Auth as the sole factor. Introduce rate limiting per IP or API key, and consider adding a lightweight second factor or monitoring for abnormal login patterns. The following example shows a Sails controller that safely handles Basic Auth credentials while incorporating rate limiting and strict validation.

// config/routes.js
module.exports.routes = {
  'POST /api/login': 'AuthController.basicLogin'
};

// api/controllers/AuthController.js
const rateLimit = require('rate-limiter-flexible');

const loginLimiter = new rateLimit.RateLimiterMemory({
  points: 5, // allow 5 attempts
  duration: 60 // per 60 seconds
});

module.exports = {
  async basicLogin(req, res) {
    const authHeader = req.headers.authorization;
    if (!authHeader || !authHeader.startsWith('Basic ')) {
      return res.status(401).json({ error: 'Missing or invalid Authorization header.' });
    }

    try {
      const base64 = authHeader.split(' ')[1];
      const decoded = Buffer.from(base64, 'base64').toString('utf-8');
      const [username, password] = decoded.split(':');

      if (!username || !password) {
        return res.status(400).json({ error: 'Invalid credentials format.' });
      }

      // Apply rate limiting to the IP or a derived identifier
      const key = req.ip;
      await loginLimiter.consume(key);

      // Replace with your user lookup and constant-time comparison
      const user = await User.findOne({ username });
      if (!user || user.password !== hashCompare(password, user.salt)) {
        return res.status(401).json({ error: 'Invalid credentials.' });
      }

      // Issue a session token or JWT instead of reusing Basic Auth
      const token = jwt.sign({ id: user.id, scope: 'api' }, process.env.JWT_SECRET, { expiresIn: '1h' });
      return res.json({ token });
    } catch (err) {
      sails.log.warn('Auth error:', err);
      return res.status(401).json({ error: 'Authentication failed.' });
    }
  }
};

// utils/hashCompare.js
// Example constant-time comparison stub
module.exports = function hashCompare(input, storedHash) {
  const crypto = require('crypto');
  const derived = crypto.pbkdf2Sync(input, storedHash.salt, 100000, 64, 'sha512').toString('hex');
  // Use timing-safe compare in production
  return derived === storedHash.hash;
};

These changes ensure that even if credentials are intercepted, they cannot be reused easily, and automated attempts are constrained. For broader coverage, integrate middleBrick into your workflow using the CLI (middlebrick scan <url>) or the GitHub Action to add API security checks to your CI/CD pipeline, and use the dashboard to track security scores over time.