Insecure Deserialization in Adonisjs with Mutual Tls

Insecure deserialization in AdonisJS applications that also use mutual TLS (mTLS) can arise when serialized objects are accepted over authenticated channels. mTLS ensures the client presenting the request possesses a valid certificate, but it does not inherently validate the safety of the serialized payload. If an endpoint deserializes attacker-controlled data (for example, parsing a serialized session, cookie, or message), an attacker who has obtained a valid client certificate can still supply maliciously crafted payloads. Common vulnerable patterns include using insecure object deserialization libraries, directly unmarshalling user input, or relying on default serialization formats without integrity checks.

Consider an AdonisJS route that receives a serialized authentication token over an mTLS-terminated connection:

// routes.ts
Route.post('/profile', async ({ request }) => {
  const serialized = request.input('token')
  const payload = deserializeToken(serialized) // insecure deserialization
  return { user: payload.user }
})

If deserializeToken performs unsafe deserialization (e.g., using a library that reconstructs objects without schema validation), an authenticated client with a valid mTLS certificate can provide a serialized payload that executes unintended code or alters object prototypes. This becomes a deserialization gadget chain attack, potentially leading to remote code execution or privilege escalation even though TLS client authentication succeeded.

Additionally, serialized data may be stored or forwarded, and later deserialized in a less trusted context. In AdonisJS, background jobs or event consumers that process messages from a queue may encounter serialized content originally produced by an mTLS-authenticated client. If the consumer trusts the source because it originated from an authenticated channel, it may skip validation and deserialize unsafely. This illustrates that mTLS secures transport and client identity, but does not replace input validation and secure deserialization practices.

Real-world parallels include scenarios where session stores or API tokens are serialized with formats that allow gadget chains (e.g., certain PHP object injection patterns have analogues in Node.js when using unsafe deserialization modules). AdonisJS developers should treat serialized data from any client—even those presenting mTLS certificates—as untrusted and validate structure, apply integrity checks (e.g., signatures), and avoid reconstructing objects from raw serialized input.

Remediation focuses on secure deserialization and proper mTLS integration. Do not deserialize untrusted data; if you must process serialized input, use strict schema validation and avoid language-level object reconstruction. In AdonisJS, prefer JSON with schema validation (e.g., using Joi or Zod) over custom binary or language-native serialization formats. If mTLS is terminating at the proxy or load balancer, ensure AdonisJS receives authenticated metadata (like client certificate details) via trusted headers set by the proxy, and validate those headers appropriately.

Example of safe JSON-based input with Zod validation in AdonisJS:

// start/hooks.ts
import { defineConfig } from '@adonisjs/core/app'
import { cors } from '@adonisjs/cors'

export default defineConfig({
  imports: [
    () => import('@adonisjs/cors'),
  ],
  http: {
    middleware: {
      cors: cors.middleware,
    },
  },
})

// controllers/ProfileController.ts
import { HttpContextContract } from '@ioc:Adonis/Core/HttpContext'
import { z } from 'zod'

const profileSchema = z.object({
  userId: z.string().uuid(),
  action: z.enum(['view', 'edit']),
})

export default class ProfileController {
  public async updateProfile({ request }: { request: HttpContextContract['request'] }) {
    const payload = profileSchema.parse(request.body())
    // Safe: payload conforms to expected shape
    return { userId: payload.userId, action: payload.action }
  }
}

If mTLS is used, configure the AdonisJS application to trust the proxy and read client certificate information securely:

// start/hooks.ts
import { defineConfig } from '@adonisjs/core/app'

export default defineConfig({
  https: {
    clientCertificateVerification: 'required',
    trustedCerts: ['/path/to/ca-bundle.pem'],
  },
})

// middleware/verify-client-cert.ts
import { HttpContextContract } from '@ioc:Adonis/Core/HttpContext'

export default async function verifyClientCert({ request, response }: HttpContextContract) {
  const cert = request.headers.get('x-client-cert')
  if (!cert) {
    response.unauthorized('Client certificate required')
    return
  }
  // Validate certificate fields as needed (issuer, CN, extensions)
  // For example, ensure it's issued by your expected CA
  const isValid = validateCertificate(cert) // implement validation logic
  if (!isValid) {
    response.unauthorized('Invalid client certificate')
  }
}

function validateCertificate(cert: string): boolean {
  // Simplified: in practice, use a library to parse and verify the certificate
  return cert.includes('YOUR_CA_FINGERPRINT')
}

For TLS termination at the edge (e.g., load balancer), forward client certificate details via headers and enforce strict validation in middleware rather than relying on mTLS at the application layer. This approach keeps deserialization safe and ensures that identity claims are verified consistently.

Finally, audit your dependencies for known vulnerabilities related to deserialization (e.g., prototype pollution gadgets in JavaScript libraries) and apply updates promptly. Combine secure coding practices with mTLS to reduce the attack surface without assuming that transport-layer authentication alone prevents application-layer attacks.