Arp Spoofing in Hanami with Api Keys

Arp spoofing is a Layer 2 attack where an attacker sends falsified ARP messages to associate their MAC address with the IP address of a legitimate host, typically the gateway or another API service. In Hanami applications that rely on static API keys for authorization, this attack can expose a critical risk when API keys are transmitted over a locally compromised network segment.

When an API key is sent as a static credential in headers such as Authorization: ApiKey <key>, and the traffic between the client and Hanami application traverses a shared network (e.g., an office LAN or a compromised Wi‑Fi segment), an attacker performing arp spoofing can intercept and observe these requests. Because API keys do not rotate per session and are often long‑lived, captured keys can be reused to impersonate services or users until the key is rotated. MiddleBrick’s unauthenticated scan checks for unencrypted transmission of API keys and flags scenarios where credentials move across the network in a way that is observable via ARP manipulation.

The risk is compounded when Hanami applications expose unauthenticated endpoints that return sensitive data and accept API key headers without enforcing transport integrity. An attacker who successfully spoofs ARP frames can position themselves as a man-in-the-middle, capturing API key values and potentially replaying them to gain unauthorized access. This maps to the Authentication and Data Exposure checks in middleBrick’s 12 parallel security checks, and findings may align with common weaknesses such as CWE‑319 (Cleartext Transmission of Sensitive Information). The scanner does not perform active ARP spoofing; instead, it analyzes whether the application’s unauthenticated attack surface allows interception of static API keys by flagging missing encryption and weak transport practices.

Using middleBrick’s OpenAPI/Swagger analysis, the scanner cross‑references spec definitions with runtime behavior to detect whether API key security schemes are defined but not enforced over TLS. If the spec declares securitySchemes using an apiKey type but the server does not mandate https, the scan reports a Data Exposure finding with remediation guidance to enforce transport layer protections.

To mitigate arp spoofing risks when using API keys in Hanami, ensure keys are never sent over cleartext connections and are handled with strict transport and storage policies. Below are concrete, syntactically correct examples for securing API keys in a Hanami application.

1. Enforce HTTPS for all API key transmissions

Configure your Hanami application to reject non‑TLS requests and ensure API keys are only accepted over HTTPS. In config/application.rb, set the following to redirect HTTP to HTTPS and enable secure cookies:

# config/application.rb
module MyApp
  class Application < Hanami::Application
    configure do |config| 
      config.force_ssl = true
      config.session_cookie_secure = true
    end
  end
end

2. Use secure header-based API key authentication with rotation

Define a security scheme that requires an API key in the X-API-Key header and validate it against a rotated value stored securely. Example request handling in a Hanami action:

# lib/app/actions/api/v1/base_action.rb
module App
  module Actions
    module Api
      module V1
        class BaseAction < Hanami::Action
          def before?(request)
            provided = request.env['HTTP_X_API_KEY']
            expected = ENV['HANAMI_API_KEY_V2'] # rotate periodically
            halt 401, { error: 'Unauthorized' }.to_json unless ActiveSupport::SecurityUtils.secure_compare(provided, expected)
            super
          end
        end
      end
    end
  end
end

In this example, secure_compare prevents timing attacks, and the key is sourced from an environment variable, avoiding hardcoded strings. Rotate HANAMI_API_KEY_V2 regularly and update it in your deployment secrets.

3. Apply API key scoping and short lifetimes where possible

While API keys are often long‑lived, you can reduce the impact of interception by scoping keys to specific endpoints or roles and using middleware to enforce context. For example, a custom middleware can validate key usage per route:

# lib/app/middleware/api_key_scope.rb
class ApiKeyScope
  def initialize(app)
    @app = app
  end

  def call(env)
    request = Rack::Request.new(env)
    if request.path.start_with?('/admin') && request.get?
      key = request.env['HTTP_X_API_KEY']
      halt_unless_valid_admin_key(key)
    end
    @app.call(env)
  end

  private

  def halt_unless_valid_admin_key(key)
    halt 403, { error: 'Forbidden' }.to_json unless key == ENV['ADMIN_API_KEY']
  end
end

# config/initializers/middleware.rb
Rack::Builder.new do
  use ApiKeyScope
  run App::Web
end

4. Store keys securely and audit access

Never commit API keys to version control. Use environment variables or a secrets manager, and ensure your CI/CD pipeline references them securely. middleBrick’s Pro plan includes continuous monitoring that can alert you if an API key appears in unexpected locations or if the risk score drops due to exposed credentials.