Api Key Exposure in Hanami with Mongodb

When a Hanami application uses a MongoDB backend, API key exposure often occurs through insecure logging, misconfigured error responses, or improper handling of connection strings and database credentials. Hanami’s object-oriented architecture encourages developers to encapsulate configuration in environment variables and service objects, but if those keys are inadvertently included in logs, stack traces, or rendered responses, they can be exposed to unauthenticated attackers.

In a black-box scan, middleBrick tests for unauthenticated endpoints that disclose internal paths, configuration snippets, or data structure details that can hint at how MongoDB is integrated. For example, an endpoint that returns a wrapped MongoDB document may include internal field names or connection identifiers that, when combined with known MongoDB default ports or deployment patterns, increase the risk of targeted follow-up attacks such as SSRF or unauthorized database enumeration.

Another common exposure vector in the Hanami + MongoDB context is the use of verbose MongoDB driver exceptions in development or improperly guarded production code. These exceptions can reveal database names, collection names, or even partial connection URIs in error messages returned to the client. middleBrick’s Data Exposure and Input Validation checks detect such disclosures by analyzing HTTP responses for patterns resembling MongoDB connection strings or authentication tokens.

Additionally, if the Hanami app serves API routes that proxy or interact with MongoDB without strict input validation, an attacker might probe for information leakage through error payloads. For instance, a malformed query that triggers a MongoDB driver exception could return a stack trace containing the host, port, and key used for the connection. middleBrick’s error scanning capabilities flag these as high-severity findings, emphasizing the need to sanitize outputs and enforce strict input validation.

Compliance mappings are relevant here: findings related to API key exposure in this context align with OWASP API Top 10 (2023) A01: Broken Object Level Authorization when exposed references allow enumeration, and A05: Security Misconfiguration when default or debug settings reveal sensitive backend details. PCI-DSS and SOC2 controls also require protection of authentication materials, including any keys used to access backend stores like MongoDB.

To mitigate API key exposure when using MongoDB with Hanami, apply defensive coding practices and configuration hygiene. Always store connection strings and keys in environment variables, never in source code or initializer files that might be committed to version control. Use Hanami’s built-in configuration mechanisms to inject these values securely at runtime.

Ensure that MongoDB driver exceptions are caught and transformed into generic error responses that do not expose internal details. Avoid passing raw driver errors to the HTTP response layer. In Hanami, you can wrap database interactions in service objects that normalize exceptions.

Secure Hanami + MongoDB code example

require 'hanami/action'
require 'mongo'

module Web::Controllers::Items
  class Show
    include Hanami::Action

    def initialize(mongo_client: Mongo::Client.new([ENV['MONGODB_URI']], database: ENV['MONGODB_DB']))
      @mongo_client = mongo_client
    end

    def call(params)
      begin
        item_id = params.fetch('id')
        collection = @mongo_client[:items]
        document = collection.find(_id: item_id).first

      rescue Mongo::Error::OperationFailure => e
        # Log full details server-side only
        Hanami.logger.error("MongoDB operation failed: #{e.message}")
        raise Web::Action::Errors::ServerError, 'Unable to retrieve item'

      rescue => e
        Hanami.logger.error("Unexpected error: #{e.class} - #{e.message}")
        raise Web::Action::Errors::ServerError, 'An unexpected error occurred'
      end

      if document
        # Return only safe, public fields
        { status: 200, body: { id: document['_id'], name: document['name'] } }
      else
        { status: 404, body: { error: 'Not found' } }
      end
    end
  end
end

Key remediation steps

• Environment configuration: Use ENV['MONGODB_URI'] and ENV['MONGODB_DB'] to inject connection strings at runtime, avoiding hardcoded values.
• Exception handling: Catch Mongo::Error::OperationFailure and generic exceptions separately. Log full details internally, but return generic error messages to the client.
• Response sanitization: Return only necessary public fields from MongoDB documents. Avoid echoing internal keys like _id directly if it exposes sensitive patterns; consider mapping to safe identifiers.
• Input validation: Validate and sanitize all incoming parameters before constructing MongoDB queries to prevent injection and error-based leakage.

middleBrick’s Pro plan supports continuous monitoring, which can be valuable here to detect regressions in how errors or logs might expose MongoDB-related details over time. You can integrate the CLI into scripts or use the GitHub Action to enforce that no commit introduces insecure patterns that could lead to API key exposure.