Dangling Dns in Adonisjs with Firestore

A dangling DNS record occurs when a DNS entry points to a resource that no longer exists or is misconfigured. In the context of an AdonisJS application that uses Google Cloud Firestore, this typically arises during environment changes such as project deletion, bucket relocation, or domain migration. If the application’s configuration retains an old or incorrect DNS name—such as a Firestore REST endpoint or a custom domain pointing to a removed backend—the client may resolve that name to an unintended host.

When AdonisJS loads environment variables (e.g., FIRESTORE_DOMAIN or a custom API base URL), it may construct Firestore requests using that value. If the DNS record is dangling, resolution can return a stale IP, an unrelated service, or trigger a fallback that bypasses intended network controls. Because the scan operates in black-box mode without credentials, it can detect unexpected responses from unauthenticated endpoints, surface open redirects, or identify information leakage through error messages that reveal internal hostnames or project IDs.

For LLM/AI Security, note that a dangling DNS setup can expose system prompt leakage patterns if error responses from misconfigured endpoints inadvertently reveal model or project metadata. Active prompt injection probes may detect inconsistent host resolution that aids an attacker in mapping the infrastructure. Output scanning may flag API keys or tokens if misrouted requests are logged by unintended services. The scan’s inventory management checks will highlight mismatched or orphaned DNS entries that correlate with unauthenticated endpoints, and unsafe consumption findings can appear if the application does not validate the resolved destination before use.

In practical terms, the risk emerges from the interaction between AdonisJS’s runtime configuration, Firestore endpoint resolution, and DNS state. Without strict validation of the target host and enforced use of authorized service endpoints, the application may communicate with an unpredictable host, violating expected trust boundaries and expanding the unauthenticated attack surface that middleBrick assesses across its 12 parallel checks.

Remediation focuses on hardcoding or validating the Firestore endpoint, ensuring DNS consistency, and tightening configuration handling in AdonisJS. Always use official Firestore SDK endpoints rather than constructing custom base URLs, and avoid environment variables that can become stale.

1. Use the official Firestore SDK with explicit project configuration

Initialize Firestore through the AdonisJS provider pattern so the endpoint is managed by the SDK and not by mutable environment variables. This reduces the risk of a dangling DNS entry being used at runtime.

// start/app_provider.ts
import { defineProvider } from '@ioc:Adonis/Core/Provider'
import { Firestore } from '@google-cloud/firestore'

export default class AppProvider {
  public async register() {
    this.container.singleton('Firestore', () => {
      return new Firestore({
        projectId: process.env.FIRESTORE_PROJECT_ID,
        // Avoid custom host; let the SDK resolve the correct endpoint
      })
    })
  }
}

2. Validate and lock the Firestore host in HTTP client requests (if used directly)

If you perform raw HTTP calls to Firestore APIs, validate the hostname against an allowlist and do not rely on environment variables that may become dangling.

// services/firestore_service.ts
import { Http } from '@ioc:Adonis/Core/Http'

export class FirestoreService {
  private readonly allowedHost = 'firestore.googleapis.com'

  public async getDocument(collection: string, docId: string) {
    const url = new URL(`https://${this.allowedHost}/v1/projects/${process.env.GCP_PROJECT_ID}/databases/(default)/documents/${collection}/${docId}`)

    // Ensure the hostname matches the allowlist
    if (new URL(url.href).hostname !== this.allowedHost) {
      throw new Error('Invalid Firestore host')
    }

    const response = await Http.get(url.href, {
      headers: {
        Authorization: `Bearer ${process.env.GCP_SERVICE_ACCOUNT_TOKEN}`
      }
    })
    return response.body
  }
}

3. Enforce DNS and environment integrity during deployment

Use CI/CD checks to verify that environment variables such as FIRESTORE_DOMAIN or custom base URLs resolve to expected hosts and are not empty or malformed. The middleBrick GitHub Action can be added to fail builds if risk scores degrade or if inventory checks detect unresolved or orphaned endpoints.

// Example CI validation step (conceptual)
if [[ -z "${FIRESTORE_PROJECT_ID}" ]]; then
  echo 'FIRESTORE_PROJECT_ID is required'
  exit 1
fi
# Optionally resolve and verify hostname
resolved=$(dig +short "${FIRESTORE_DOMAIN}" | head -n1)
if [[ "$resolved" != "172.217.0.0"* ]]; then
  echo "Unexpected Firestore DNS resolution: $resolved"
  exit 1
fi

4. Apply middleware to sanitize outbound requests

In AdonisJS, use middleware to validate outbound HTTP destinations when your application interacts with external services. This ensures that even if configuration is compromised, the request does not silently resolve to a dangling or malicious host.

// middleware/validate_firestore_host.ts
import { HttpContextContract } from '@ioc:Adonis/Core/HttpContext'

export default async function validateFirestoreHost({ request }: HttpContextContract) {
  const host = request.url().hostname
  if (host !== 'firestore.googleapis.com') {
    throw new Error('Blocked request to non-whitelisted Firestore host')
  }
}