Heap Overflow in Adonisjs with Basic Auth

A heap overflow in AdonisJS when Basic Auth is used typically arises from unchecked input handling in the authentication layer and downstream request processing. When Basic Auth credentials are parsed, the username and password are often extracted directly from the Authorization header without strict length or type validation. If an attacker sends an extremely long or malformed credential string, the runtime may allocate a buffer on the heap that is smaller than the incoming data. Subsequent copying or formatting operations can overflow this buffer, corrupting adjacent memory. Because AdonisJS runs on Node.js, the observable effect may not be a classic exploitable memory corruption as in lower-level languages, but the pattern still represents a denial-of-service risk and can expose internal objects or stack traces through error messages.

The combination of Basic Auth and unchecked input becomes critical when the parsed credentials are passed into business logic, logging, or serialization routines. For example, using the parsed user object in string concatenation or JSON serialization without sanitization can amplify abnormal heap behavior. Furthermore, if the endpoint relies on OpenAPI/Swagger specs where the security scheme is defined as Basic Auth but input validation is weak, the runtime may fail to enforce boundaries, allowing oversized payloads to traverse multiple middlewares. This chain increases the attack surface across the 12 security checks, particularly Input Validation and Data Exposure, because malformed credentials may trigger verbose stack traces or leak sensitive information in responses.

When you scan such an endpoint with middleBrick, the scanner’s unauthenticated approach sends oversized Authorization headers and observes how the application handles them. The tool checks whether the server returns consistent error formats, enforces reasonable credential length limits, and avoids exposing internal structures. Findings may highlight missing length validation for Basic Auth credentials, improper error handling that reveals internal state, and inconsistent behavior between spec definitions and runtime behavior. Remediation focuses on strict validation, bounded parsing, and defensive coding to ensure heap allocations remain safe and error messages do not disclose sensitive data.

To mitigate heap-related risks with Basic Auth in AdonisJS, enforce strict validation on the Authorization header before parsing. Always limit the size of incoming credentials and reject requests that exceed a reasonable threshold. Use a dedicated middleware to inspect and sanitize credentials, and avoid passing raw header values into business logic or logs. Below are concrete code examples demonstrating these practices.

Example 1: Validating Authorization header length and format

import { HttpContextContract } from '@ioc:Adonis/Core/HttpContext'

export default class AuthMiddleware {
  public async handle({ request, response, proceed }: HttpContextContract) {
    const authHeader = request.headers().authorization
    if (!authHeader || !authHeader.startsWith('Basic ')) {
      return response.unauthorized({ message: 'Missing or invalid Basic Auth header' })
    }

    // Limit the header length to prevent oversized payloads
    if (authHeader.length > 500) {
      return response.badRequest({ message: 'Authorization header too long' })
    }

    const base64 = authHeader.split(' ')[1]
    if (!base64 || base64.length > 400) {
      return response.badRequest({ message: 'Invalid credential encoding' })
    }

    // Proceed after validation
    return proceed()
  }
}

Example 2: Sanitizing credentials and avoiding exposure

import { createHash } from 'crypto'
import { HttpContextContract } from '@ioc:Adonis/Core/HttpContext'

export default class AuthController {
  public async login({ request, response }: HttpContextContract) {
    const authHeader = request.headers().authorization
    if (!authHeader || !authHeader.startsWith('Basic ')) {
      return response.unauthorized({ message: 'Authentication required' })
    }

    const payload = Buffer.from(authHeader.split(' ')[1], 'base64').toString('utf8')
    const [username, password] = payload.split(':')

    // Enforce strict bounds on username and password
    if (!username || !password || username.length > 100 || password.length > 200) {
      return response.badRequest({ message: 'Invalid credentials length' })
    }

    // Avoid logging raw credentials; log hashes or masked values only
    const usernameHash = createHash('sha256').update(username).digest('hex')
    console.info(`Auth attempt for user hash: ${usernameHash}`)

    // Perform authentication logic here (e.g., compare hashed credentials)
    // ...

    return response.ok({ message: 'Authenticated' })
  }
}

Example 3: Integrating with OpenAPI spec validation

Ensure your OpenAPI/Swagger definitions define security schemes and constraints explicitly. Use request validation libraries compatible with AdonisJS to enforce schema rules at runtime. For instance, define max lengths for header fields in the spec and validate against them.

// openapi.yaml excerpt
securitySchemes:
  basicAuth:
    type: http
    scheme: basic
    x-max-header-length: 500

paths:
  /secure:
    get:
      security:
        - basicAuth: []
      responses:
        '200':
          description: OK

By combining middleware validation, strict bounds on credential sizes, and spec-driven checks, you reduce the risk of heap-related anomalies and ensure more predictable behavior under malformed input.