Need

Ensuring complete and secure code functionality

Context

• Usage of Dart 2.0 for developing high-performance web and mobile applications
• Usage of dart:io for handling input and output operations in Dart programming
• Usage of the shelf package in Dart for building web applications and HTTP middleware.
• Usage of the shelf_io package for handling HTTP requests in Dart with the Shelf framework

Description

Non 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);
}

shelf.Response _echoRequest(shelf.Request request) {
  var file = new File('binary_file.bin');
  var contents;

  // Read file content
  contents = file.readAsBytesSync();

  return new shelf.Response.ok(contents);
}
        
        

In the given Dart code, a server is created using the Shelf framework. The server listens on localhost at port 8080 and responds to all incoming requests by reading and returning the contents of a binary file named binary_file.bin.

The binary file is read synchronously using the readAsBytesSync method and the contents are sent as the response to the client.

This code is vulnerable as it involves serving a binary file without its corresponding source code. This binary file could contain malicious code or sensitive information. Plus, the file is being read synchronously, which can block the server from handling other requests until the file is fully read.

Moreover, if the binary contains sensitive information, it is being sent unencrypted over the network, thus exposing it to potential eavesdropping or man-in-the-middle attacks.

Steps

• Remove the binary file from the repository. If it's necessary for the application, replace it with its source code.
• If the binary file contains sensitive information, ensure it is encrypted and securely stored. The decryption key should be securely managed and not hard-coded in the application.
• If the binary file is being used for some functionality, consider implementing that functionality directly in the application code.
• If the binary file is a third-party library or tool, check if there is a trusted source where it can be downloaded during the build process instead of storing it in the repository.
• Ensure that the application does not expose the contents of the binary file through its endpoints. If the file needs to be served, it should be done securely and only to authenticated and authorized users.

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);
}

shelf.Response _echoRequest(shelf.Request request) {
  // Removed the code that reads and returns the binary file
  return new shelf.Response.ok('Hello, World!');
}
        
        

The original code had a vulnerability where it was reading a binary file and returning its contents as a response. This is a security risk as binary files can contain sensitive information, and they can also be malicious or have vulnerabilities.

The binary file has been removed from the repository. If it's necessary for the application, it should be replaced with its source code. If the binary file contains sensitive information, it should be encrypted and securely stored. The decryption key should be securely managed and not hard-coded in the application.

If the binary file is being used for some functionality, consider implementing that functionality directly in the application code. If the binary file is a third-party library or tool, check if there is a trusted source where it can be downloaded during the build process instead of storing it in the repository.

The application no longer exposes the contents of the binary file through its endpoints. If the file needs to be served, it should be done securely and only to authenticated and authorized users.

References

• 233. Incomplete funcional code