Credential Stuffing in Restify

Credential stuffing attacks exploit the reuse of username/password combinations across multiple services. In Restify applications, these attacks typically manifest through several Restify-specific patterns and vulnerabilities.

The most common attack vector involves automated scripts sending POST requests to Restify's authentication endpoints. Since Restify's server.post('/login', handler) routes are stateless by default, attackers can rapidly iterate through credential lists without triggering built-in protections. The framework's minimalist design means developers must explicitly implement rate limiting and authentication safeguards.

Restify's server.use(restify.plugins.authorizationParser()) middleware can be exploited when combined with weak session management. Attackers often target endpoints that return different error messages for valid vs invalid usernames, allowing them to enumerate valid accounts before launching credential stuffing attacks.

Another Restify-specific manifestation occurs in API versioning scenarios. When using server.use(restify.plugins.acceptVersion('1.0.0', '2.0.0')), older API versions might lack modern security protections, creating attack surfaces that bypass newer security implementations.

Rate limiting in Restify requires explicit configuration. Without server.use(restify.plugins.throttle({burst: 10, rate: 0.5, ip: true})), endpoints remain vulnerable to high-volume credential stuffing attempts. The framework's default behavior allows unlimited requests, making it particularly susceptible to automated attacks.

Restify's server.get('/me', handler) endpoints for user profile access can leak information through timing differences or error messages, helping attackers validate credential combinations even when authentication fails.

JSON body parsing in Restify (server.use(restify.plugins.bodyParser())) can be exploited when not properly configured with size limits, allowing attackers to send large credential payloads that strain server resources during credential stuffing campaigns.

Detecting credential stuffing in Restify applications requires monitoring specific patterns and implementing detection mechanisms at the framework level.

Log analysis is crucial. Restify's built-in audit logger (server.on('after', restify.plugins.auditLogger({log: bunyanLogger}))) can be configured to track authentication failures. Look for patterns like:

// Detect suspicious patterns in audit logs
const suspiciousPatterns = {
  rapidAuthFailures: (logs, threshold = 50) => {
    const failures = logs.filter(l => 
      l.statusCode === 401 && 
      l.time > Date.now() - 300000
    );
    return failures.length > threshold;
  },
  geographicAnomalies: (logs) => {
    const ips = logs.map(l => l.request.remoteAddress);
    const countries = ips.map(ip => geoip.lookup(ip)).filter(c => c);
    return countries.length > 3 && countries.every(c => c.country !== 'US');
  }
};

Request fingerprinting helps identify automated tools. Restify's req.headers['user-agent'] and timing analysis can reveal non-human patterns. Implement middleware to track request cadence:

const credentialStuffingDetector = (req, res, next) => {
  const now = Date.now();
  const ip = req.connection.remoteAddress;
  
  if (!req.attackData) {
    req.attackData = {
      requests: [],
      authAttempts: 0,
      lastAuth: 0
    };
  }
  
  req.attackData.requests.push(now);
  
  // Remove requests older than 1 minute
  req.attackData.requests = req.attackData.requests.filter(t => now - t < 60000);
  
  // Flag if more than 100 requests from same IP in 1 minute
  if (req.attackData.requests.length > 100) {
    console.warn(`Potential credential stuffing from ${ip}`);
  }
  
  next();
};

middleBrick's scanning specifically targets Restify authentication patterns. The scanner identifies:

• Unprotected authentication endpoints that accept POST requests without rate limiting
• API endpoints that leak information through error messages
• Missing restify.plugins.throttle middleware on sensitive routes
• Improper configuration of restify.plugins.authorizationParser()
• Endpoints vulnerable to timing attacks during credential validation

The scanner tests these endpoints by sending legitimate-looking authentication requests and analyzing response patterns, helping identify vulnerable Restify implementations before attackers can exploit them.

Securing Restify applications against credential stuffing requires implementing multiple layers of protection using Restify's native capabilities and complementary security measures.

Rate limiting is the first line of defense. Configure Restify's throttle plugin at the application level:

const restify = require('restify');
const server = restify.createServer();

// Global rate limiting
server.use(restify.plugins.throttle({
  burst: 10,           // Max burst requests
  rate: 0.5,          // Sustained rate (requests/second)
  ip: true,           // Rate limit by IP
  overrides: {
    '192.168.1.1': {
      burst: 0,
      rate: 0
    }
  }
}));

// Stricter limits on authentication endpoints
server.post('/login', 
  restify.plugins.throttle({
    burst: 5,
    rate: 0.2,
    ip: true
  }),
  authenticateHandler
);

Implement CAPTCHA or similar challenges after failed attempts:

const failedAttempts = new Map();

const loginHandler = (req, res, next) => {
  const ip = req.connection.remoteAddress;
  const now = Date.now();
  
  if (!failedAttempts.has(ip)) {
    failedAttempts.set(ip, {count: 0, firstFailure: now});
  }
  
  const data = failedAttempts.get(ip);
  
  // Reset after 15 minutes
  if (now - data.firstFailure > 900000) {
    data.count = 0;
    data.firstFailure = now;
  }
  
  // Require CAPTCHA after 3 failed attempts
  if (data.count >= 3) {
    if (!req.body.captcha || !verifyCaptcha(req.body.captcha)) {
      return res.send(400, {error: 'CAPTCHA required'});
    }
  }
  
  // Authenticate...
  if (!authenticate(req.body.username, req.body.password)) {
    data.count++;
    return res.send(401, {error: 'Invalid credentials'});
  }
  
  // Successful login, reset counter
  data.count = 0;
  next();
};

Implement IP-based blocking for repeated offenders:

const blockedIPs = new Set();
const blockList = new Map();

const ipBlocker = (req, res, next) => {
  const ip = req.connection.remoteAddress;
  
  if (blockedIPs.has(ip)) {
    const block = blockList.get(ip);
    if (Date.now() - block.since < block.duration) {
      return res.send(429, {error: 'IP temporarily blocked'});
    } else {
      blockedIPs.delete(ip);
      blockList.delete(ip);
    }
  }
  
  next();
};

Use Restify's built-in security headers and request validation:

// Security middleware
server.use(restify.plugins.conditionalRequest());
server.use(restify.plugins.security());

server.use((req, res, next) => {
  // Validate request size
  if (req.headers['content-length'] > 1000) {
    return res.send(413, {error: 'Request too large'});
  }
  
  // Check for suspicious patterns
  if (/admin/i.test(req.body.username)) {
    console.warn(`Suspicious username attempt: ${req.body.username}`);
  }
  
  next();
});

Implement proper error handling to avoid information leakage:

const authenticateHandler = (req, res, next) => {
  const {username, password} = req.body;
  
  try {
    const user = await findUser(username);
    if (!user) {
      // Always perform hash comparison to prevent timing attacks
      await bcrypt.compare(password, '$2b$12$invalidhash');
      return res.send(401, {error: 'Invalid credentials'});
    }
    
    const valid = await bcrypt.compare(password, user.passwordHash);
    if (!valid) {
      return res.send(401, {error: 'Invalid credentials'});
    }
    
    // Successful authentication
    req.user = user;
    next();
    
  } catch (err) {
    console.error('Authentication error:', err);
    return res.send(500, {error: 'Authentication failed'});
  }
};

middleBrick's remediation guidance specifically addresses Restify's architecture. The scanner identifies missing rate limiting, inadequate error handling, and vulnerable authentication patterns, then provides Restify-specific fixes like the examples above. The tool maps findings to OWASP API Top 10 categories and provides prioritized remediation steps based on severity.