Dns Cache Poisoning in Feathersjs with Basic Auth

DNS cache poisoning (also known as DNS spoofing) occurs when an attacker injects forged DNS responses into a resolver’s cache, causing a domain to resolve to a malicious IP. In a Feathersjs application that uses Basic Auth, the risk surface is shaped by how the client resolves the service hostname and how credentials are transmitted.

Feathersjs clients typically make HTTP requests to a configured host and port. If the hostname is resolved via a shared or vulnerable resolver—such as a container runtime, a recursive resolver shared across a network, or a misconfigured system resolver—an attacker on the network or positioned between the resolver and the authoritative nameservers can poison the cache. Once poisoned, any request to that hostname resolves to the attacker’s machine.

When Basic Auth is used, credentials are sent in the Authorization header as base64-encoded username:password. Note that base64 is not encryption; it is easily decoded. If DNS cache poisoning redirects the client to a rogue server, the client will send the Authorization header to that attacker. While the attacker cannot directly derive the password from the base64 string without decoding, the stolen credentials can be replayed immediately or captured and later used in other systems where the same credentials are reused.

The combination is particularly dangerous when Feathersjs services are deployed in environments with shared networking—such as Kubernetes pods or container orchestration platforms—where DNS behavior may be influenced by node-level resolvers or sidecar proxies. In such setups, a poisoned cache can redirect traffic from multiple services, increasing the blast radius. Moreover, if logging or error handling inadvertently exposes stack traces or endpoint paths, an attacker gains further context to refine follow-up attacks.

To contextualize this within the 12 security checks run by middleBrick, DNS-related misconfigurations often surface under findings like SSRF or Data Exposure when internal hostnames leak, or under Unsafe Consumption when external input influences service resolution. The scanner evaluates whether the API’s runtime behavior aligns with its OpenAPI/Swagger spec, cross-referencing definitions and runtime responses to detect inconsistencies that could enable or indicate DNS manipulation.

middleBrick’s LLM/AI Security checks are relevant here because they detect System prompt leakage and probe for output handling issues; while not directly testing DNS, they ensure that AI-assisted components or generated code do not introduce unsafe resolution logic or leak internal hostnames in responses, which could aid an attacker in crafting more convincing poisoning campaigns.

Remediation focuses on preventing credential exposure and ensuring that the client validates the server identity, even when DNS resolution is compromised. The following patterns demonstrate secure usage of Basic Auth in Feathersjs.

Use HTTPS and Avoid Sending Credentials on Untrusted Networks

Always prefer HTTPS to protect credentials in transit. With HTTPS, even if DNS is poisoned, the attacker cannot decrypt the Authorization header without the server’s private key. Never send Basic Auth over plain HTTP.

Pin Server Certificates or Use Public Key Pinning

Certificate pinning binds the client to a specific certificate or public key, reducing the impact of DNS poisoning. In Node.js, you can use the https agent with a custom checkServerIdentity function.

const https = require('https');
const fs = require('fs');

const pinnedCert = fs.readFileSync('/path/to/cert.pem');

const agent = new https.Agent({
  checkServerIdentity: (host, cert) => {
    const certFingerprint = crypto.createHash('sha256').update(cert.raw).digest('hex');
    const expectedFingerprint = 'YOUR_CERT_SHA256_FINGERPRINT';
    if (certFingerprint !== expectedFingerprint) {
      return new Error('Certificate pinning failure');
    }
    return undefined;
  }
});

const feathersClient = require('@feathersjs/client');
const transport = feathersClient.transport({
  path: '/',
  fetch: (url, options) => fetch(url, { ...options, agent })
});

const client = feathersClient();
client.configure(transport);
client.configure(feathersClient.authentication({
  strategy: 'jwt',
  header: 'Authorization',
  token: 'Bearer YOUR_SECURE_TOKEN'
}));

Validate Hostname and Avoid Dynamic Host Resolution

Do not construct hostnames from user input. Use a fixed, well-known hostname and ensure DNS resolution is configured securely—prefer using /etc/hosts or cluster-local DNS with restricted updates.

Example Secure Feathersjs Client with Basic Auth over HTTPS

The following example shows a Feathersjs client configured with Basic Auth over HTTPS, using a fixed endpoint and secure headers.

const feathers = require('@feathersjs/client');
const auth = require('@feathersjs/authentication-client');

const client = feathers();

// Configure transport to use HTTPS with fixed endpoint
const transport = feathers.transport({
  url: 'https://api.example.com/',
  headers: {
    // Basic Auth: encode credentials securely; do not hardcode in production
    Authorization: 'Basic ' + Buffer.from('username:password').toString('base64')
  }
});

client.configure(transport);
client.configure(auth({
  header: 'Authorization',
  strategy: 'jwt'
}));

// Use the client
client.service('messages').find()
  .then(response => console.log(response))
  .error(error => console.error('API error:', error));

Rotate Credentials and Monitor for Anomalies

Even with pinning, rotate credentials regularly. Monitor logs for repeated authentication failures or requests from unexpected IPs, which may indicate ongoing poisoning attempts.

middleBrick’s dashboard and CLI can be used to scan your API endpoints and verify that authentication headers are not exposed in logs or error messages. The scanner’s Data Exposure checks help identify whether credentials inadvertently appear in responses or metadata, complementing these remediation steps.