Dns Cache Poisoning in Adonisjs with Firestore

Dns Cache Poisoning occurs when an attacker forces a DNS resolver to cache a malicious IP mapping, redirecting traffic away from the legitimate endpoint. In AdonisJS applications that rely on Google Cloud Firestore, this attack surface emerges during service discovery and outbound HTTP communication. AdonisJS may resolve Firestore hostnames at runtime using Node’s DNS resolution, and if DNS responses are not strictly validated, a poisoned cache can redirect requests to a malicious host masquerading as Firestore.

When Firestore client libraries are used within AdonisJS services—particularly with custom HTTP agents or proxy configurations—the application may trust the first DNS result for the project’s Firestore endpoint. If an attacker compromises a recursive resolver or exploits weak resolver configurations, the poisoned record can cause the AdonisJS runtime to send credentials, tokens, or sensitive data to an attacker-controlled server. This is especially risky when applications use unauthenticated or misconfigured service accounts, as the malicious host might present a valid TLS certificate for a domain like googleapis.com, bypassing basic hostname verification.

Moreover, AdonisJS applications that dynamically construct Firestore client configurations using environment variables or runtime inputs can inadvertently amplify the impact. For example, if a hostname is derived from user-controlled data without strict validation, an attacker might inject a malicious domain that resolves to an IP under their control. The combination of AdonisJS’s dependency on external packages for DNS resolution and Firestore’s cloud endpoints creates a scenario where poisoned DNS records can lead to credential theft, data exfiltration, or manipulation of database operations.

The risk is further heightened when applications use unauthenticated endpoints or fail to enforce strict certificate pinning. Without explicit hostname verification or DNSSEC validation, the AdonisJS application may accept a spoofed response, treating the malicious IP as the legitimate Firestore service. This exposes authentication tokens, project IDs, and potentially sensitive data stored in Firestore to interception or manipulation.

To mitigate Dns Cache Poisoning in AdonisJS applications using Firestore, enforce strict hostname verification and avoid reliance on default DNS caching behavior. Use explicit endpoint configuration and validate TLS certificates against known fingerprints. Below are concrete remediation steps with code examples tailored for AdonisJS with Firestore.

1. Use a fixed endpoint with explicit host header

Instead of relying on DNS resolution at runtime, configure the Firestore client with a fixed, validated endpoint. This reduces exposure to poisoned DNS records.

import { Firestore } from '@google-cloud/firestore';

const firestore = new Firestore({
  projectId: process.env.GCP_PROJECT_ID,
  keyFilename: '/path/to/service-account.json',
  customHeaders: {
    'x-goog-api-client': 'adal-node/1.2.0 gl-node/18.11.0'
  },
  // Explicitly set the host to a known, trusted endpoint
  servicePath: 'firestore.googleapis.com',
  port: 443,
});

// Verify host resolution at startup (example)
import dns from 'node:dns/promises';
const resolved = await dns.resolve4('firestore.googleapis.com');
console.log('Resolved IPs:', resolved);

2. Enforce certificate and hostname validation

Ensure that TLS connections validate the server certificate against the expected hostname. Avoid disabling certificate checks.

import { Firestore } from '@google-cloud/firestore';
import { createSecureContext } from 'tls';

const firestore = new Firestore({
  projectId: process.env.GCP_PROJECT_ID,
  keyFilename: '/path/to/service-account.json',
  sslCreds: {
    'grpc.ssl_target_name_override': 'firestore.googleapis.com',
    'grpc.default_ssl_root_cert_file': '/path/to/trusted-ca.pem',
  },
});

// Example: Validate certificate fingerprint on startup (pseudo-code)
// const expectedFingerprint = 'SHA256:...';
// const actualFingerprint = await getCertificateFingerprint('firestore.googleapis.com', 443);
// if (actualFingerprint !== expectedFingerprint) throw new Error('Certificate mismatch');

3. Restrict DNS resolution at the Node.js level

Use the dns module to set secure resolver options, such as using a trusted DNS server and disabling caching for critical resolutions.

import dns from 'node:dns';

// Use a reliable, enterprise DNS resolver
dns.setServers(['8.8.8.8', '1.1.1.1']);

// Perform a one-time resolution and cache the result securely in memory
let firestoreEndpointIP = null;
async function resolveFirestoreEndpoint() {
  const addresses = await dns.resolve4('firestore.googleapis.com', { ttl: 300 });
  firestoreEndpointIP = addresses[0];
  return firestoreEndpointIP;
}

// Use the resolved IP in custom agent (example)
import https from 'node:https';
const agent = new https.Agent({
  hostname: 'firestore.googleapis.com',
  ip: firestoreEndpointIP,
});

4. Input validation for dynamic configurations

If constructing Firestore client configuration dynamically, validate and sanitize all inputs to prevent injection of malicious hostnames.

import { Firestore } from '@google-cloud/firestore';

function createFirestoreClient(userProvidedHost) {
  const allowedHosts = ['firestore.googleapis.com', 'firestore.googleapis.com.cn'];
  const hostname = new URL(userProvidedHost).hostname;
  if (!allowedHosts.includes(hostname)) {
    throw new Error('Disallowed Firestore endpoint');
  }
  return new Firestore({
    projectId: process.env.GCP_PROJECT_ID,
    keyFilename: '/path/to/service-account.json',
    servicePath: hostname,
  });
}

5. Monitor and rotate credentials

Even with DNS hardening, rotate service account keys regularly and monitor for unusual access patterns. Use AdonisJS middleware to log and inspect outbound Firestore connections where feasible.

These measures reduce the attack surface by minimizing reliance on DNS caching and ensuring that Firestore connections are established only with validated endpoints and certificates.