Arp Spoofing in Restify with Cockroachdb

Arp spoofing is a Layer 2 attack where an adversary sends falsified ARP messages to associate their MAC address with the IP address of another host, typically the default gateway or a backend database server. When a Restify service communicates with Cockroachdb over the local network, ARP resolution on the subnet can be abused to intercept or modify traffic between the application and the database.

In a typical Restify + Cockroachdb deployment, the Node.js service resolves the database hostname to an IP, then sends SQL requests over TCP. If an attacker performs ARP spoofing on the host or the local network segment, they can redirect those TCP streams to a malicious machine. Because Cockroachdb often uses long-lived connections and may transmit sensitive data (such as authentication tokens or query results), intercepted traffic can expose credentials or data in transit. Even if Cockroachdb enforces TLS, an attacker able to terminate or modify the connection at ARP level may force the client to interact with a rogue server unless certificate validation is strictly enforced.

The exposure is specific to the combination of Restify’s runtime behavior and Cockroachdb’s network characteristics. Restify services often run in containers or shared environments where ARP visibility is higher, and Cockroachdb clusters may advertise internal IPs that are reachable across pods or nodes. Without host-level hardening (e.g., static ARP entries or filtering), the attack surface remains open during the short window between DNS lookup and TCP connection establishment. This does not imply that Restify or Cockroachdb are insecure by design; rather, the risk arises when network controls are absent, allowing a local attacker to insert themselves into the database communication path.

middleBrick scans can surface weaknesses related to network exposure and insecure service communication as part of its SSRF and Data Exposure checks, emphasizing the importance of transport protections and network segmentation. Even though middleBrick does not fix these issues, its findings can guide teams to enforce TLS, validate server certificates, and reduce reliance on implicit trust within the local network.

Remediation focuses on ensuring that Restify applications validate server identity, use strong encryption, and avoid relying on network-level implicit trust when communicating with Cockroachdb. Below are concrete examples using the node-postgres driver (common for Cockroachdb) within a Restify service.

First, enforce SSL connections and verify the server certificate. This prevents an attacker who successfully spoofs ARP from presenting a valid certificate that your client will trust.

const restify = require('restify');
const { Pool } = require('pg');

const server = restify.createServer();

const pool = new Pool({
  host: 'cockroachdb.internal.example.com',
  port: 26257,
  database: 'appdb',
  ssl: {
    rejectUnauthorized: true,
    ca: fs.readFileSync('/path/to/ca.crt').toString(),
    key: fs.readFileSync('/path/to/client.key').toString(),
    cert: fs.readFileSync('/path/to/client.crt').toString(),
  },
});

server.get('/users/:id', async (req, res, next) => {
  try {
    const { rows } = await pool.query('SELECT id, name FROM users WHERE id = $1', [req.params.id]);
    if (rows.length === 0) return next(new restify.NotFoundError('User not found'));
    res.send(rows[0]);
    next();
  } catch (err) {
    return next(new restify.InternalServerError(err.message));
  }
});

server.listen(8080, () => console.log('API listening on port 8080'));

Second, prefer connection strings that explicitly disable unencrypted modes and set acceptable TLS protocols. This reduces the risk of downgrade attacks that could be paired with ARP spoofing.

const { Pool } = require('pg');
const connectionString = 'postgresql://appuser:[email protected]:26257/appdb?sslmode=verify-full&sslcert=/path/to/client.crt&sslkey=/path/to/client.key&sslrootcert=/path/to/ca.crt';

const pool = new Pool({
  connectionString,
});

Third, implement network-level protections where possible. While not a Restify code change, binding to localhost for intra-service communication and using firewall rules to limit who can reach the Cockroachdb port reduces the feasibility of ARP spoofing from external machines on the same subnet.

Finally, monitor for unusual connection patterns. If your Restify service suddenly sees TLS handshake failures or certificate warnings when connecting to Cockroachdb, treat them as potential security incidents and investigate the network path, because ARP spoofing can sometimes trigger unexpected certificate errors when an attacker presents their own credentials.