Arp Spoofing in Feathersjs with Basic Auth

Arp spoofing is a Layer 2 attack where an attacker sends falsified ARP messages to associate their MAC address with the IP of a legitimate host, typically the gateway or another API server. In a Feathersjs application that uses Basic Auth over HTTP (no TLS), this creates a critical risk: an attacker on the same local network can intercept and modify unauthenticated or weakly protected traffic. Because Feathersjs commonly runs as a Node.js service without enforced HTTPS in development or misconfigured deployments, an attacker who successfully spoofs the MAC-to-IP bindings can position themselves as a man-in-the-middle between the client and the Feathersjs server.

When Basic Auth is used without TLS, credentials are base64-encoded but not encrypted. An attacker performing arp spoofing can capture these HTTP requests and decode the credentials easily. Even if the Feathersjs service exposes an unauthenticated endpoint as part of its black-box attack surface (as scanned by tools like middleBrick), combining that with spoofed ARP tables may allow the attacker to redirect traffic to a malicious proxy. This exposes authentication bypass opportunities, session hijacking, and potential tampering with request parameters or headers. The scanner may flag issues such as missing encryption and unsafe transmission, but the runtime risk is amplified in a local network where arp spoofing is feasible.

Feathersjs itself does not introduce the vulnerability; it is the lack of transport-layer protections combined with the inherent weakness of Basic Auth over shared media that enables exploitation. If the API relies solely on unauthenticated or low-integrity checks (for example, permissive CORS or relaxed host headers), an attacker can leverage arp spoofing to inject or modify requests. MiddleBrick’s checks for Encryption and Input Validation highlight these weaknesses, but the onus is on the developer to enforce HTTPS and avoid sending sensitive credentials in clear text, especially in environments where Layer 2 attacks are plausible.

Remediation centers on replacing Basic Auth over HTTP with HTTPS and strengthening authentication. Never transmit credentials in clear text; always enforce TLS and prefer token-based mechanisms. If you must use Basic Auth temporarily, ensure it is only over encrypted channels and augment it with additional protections such as strict host checks and request validation.

Example: Securing Feathersjs with HTTPS and proper authentication

const feathers = require('@feathersjs/feathers');
const express = require('@feathersjs/express');
const app = express(feathers());

// Enforce HTTPS in production by using a reverse proxy (e.g., Nginx) or a TLS layer
// For development, you can use self-signed certs with express middleware
const https = require('https');
const fs = require('fs');

const options = {
  key: fs.readFileSync('path/to/server.key'),
  cert: fs.readFileSync('path/to/server.crt')
};

// Configure a secure transport
app.configure(express.rest());
app.configure(express.json());
app.configure(express.urlencoded({ extended: true }));

// Example service with authentication hook to validate Basic Auth
app.use('/secure', {
  async before(hook) {
    const auth = hook.headers.authorization;
    if (!auth || !auth.startsWith('Basic ')) {
      throw new Error('Unauthorized');
    }
    const buffer = Buffer.from(auth.slice(6), 'base64');
    const [user, pass] = buffer.toString('utf-8').split(':');
    // Replace with secure credential lookup (e.g., hashed passwords)
    if (user !== 'admin' || pass !== 'S3cur3P@ss') {
      throw new Error('Invalid credentials');
    }
    hook.params.user = { id: user };
    return hook;
  }
});

// Define a simple service
app.use('/messages', {
  async find(params) {
    return [{ text: 'Hello over HTTPS' }];
  }
});

https.createServer(options, app).listen(8443, () => {
  console.log('Secure Feathersjs server running on https://localhost:8443');
});

In this example, credentials are still base64-encoded but are only transmitted over HTTPS, mitigating the risk of interception via arp spoofing. The hook validates the Authorization header and throws errors for missing or invalid credentials. For production, store user credentials as salted hashes and verify against a database or an identity provider.

Harden network and runtime environment

• Use HTTPS with strong ciphers; do not rely on Basic Auth without TLS.
• Implement host header validation and avoid exposing unnecessary endpoints.
• Employ network segmentation to limit the feasibility of arp spoofing.
• Regularly scan with middleBrick to detect missing encryption and misconfigurations.