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Insecure service configuration - OTP

Need​

Disable OTP mock in the application configuration

Context​

  • Usage of Dart 2.0 for building scalable and performant applications
  • Usage of Shelf for managing and organizing data in Node.js applications
  • Usage of shelf_io for managing and interacting with data storage in Node.js

Description​

Non compliant code​

import 'package:shelf/shelf.dart' as shelf;
import 'package:shelf/shelf_io.dart' as io;

void main() {
  var handler = const shelf.Pipeline().addMiddleware(shelf.logRequests())
      .addHandler(_echoRequest);

  io.serve(handler, 'localhost', 8080);
  print('Serving at http://localhost:8080');
}

shelf.Response _echoRequest(shelf.Request request) {
  // Mock OTP service for testing
  var otpMock = true;

  if (otpMock) {
    return shelf.Response.ok('Mock OTP Enabled');
  } else {
    // Real OTP service code
    return shelf.Response.ok('Real OTP Service');
  }
}

The above code is a simple server application using the Shelf framework in Dart. It includes a middleware that logs requests and a handler that responds to requests.

The vulnerability lies in the _echoRequest function. This function includes a boolean variable, otpMock, that is set to true. When otpMock is true, the function returns a response indicating that the mock OTP (One-Time Password) service is enabled. This mock service is likely less secure than the real OTP service, and could potentially be exploited by attackers.

In a production environment, it is crucial to ensure that all testing or mock services are disabled to prevent any potential security issues. The mock OTP service should be disabled or removed entirely once testing is complete to ensure the security of the application.

Steps​

  • Remove the OTP mock service from the production code.
  • Use environment variables or a configuration file to switch between the mock and the real OTP service.
  • Ensure that the configuration for the production environment does not include the OTP mock service.
  • Implement a proper access control for the OTP service, so only authorized users or services can use it.
  • Regularly review and update the service configuration to ensure it is secure.

Compliant code​

import 'dart:io';
import 'package:shelf/shelf.dart' as shelf;
import 'package:shelf/shelf_io.dart' as io;

void main() {
  var handler = const shelf.Pipeline().addMiddleware(shelf.logRequests())
      .addHandler(_echoRequest);

  io.serve(handler, 'localhost', 8080);
  print('Serving at http://localhost:8080');
}

shelf.Response _echoRequest(shelf.Request request) {
  // Use environment variable to switch between mock and real OTP service
  var otpMock = Platform.environment['OTP_MOCK'] == 'true';

  if (otpMock) {
    // Ensure only authorized users/services can use the mock OTP service
    if (request.headers['Authorization'] == 'Bearer valid_token') {
      return shelf.Response.ok('Mock OTP Enabled');
    } else {
      return shelf.Response.forbidden('Unauthorized access');
    }
  } else {
    // Real OTP service code
    return shelf.Response.ok('Real OTP Service');
  }
}

The code has been updated to address the insecure service configuration vulnerability. The OTP mock service is now controlled by an environment variable, OTP_MOCK. This allows for easy switching between the mock and real OTP service without having to modify the code.

In addition, an access control check has been added to the mock OTP service. It checks for a valid authorization token in the request headers. If the token is not present or invalid, the service responds with a 403 Forbidden status, indicating that the client does not have permission to access the resource.

This solution ensures that the OTP mock service is not accidentally enabled in a production environment and that only authorized users or services can use it. It is recommended to regularly review and update the service configuration to ensure it remains secure.

References​

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