Lack of data validation

Lack of data validation - URL

Need

Implementation of robust data validation for URL parameters

Context

• Usage of Dart 2.0 for building high-performance, cross-platform applications

• Usage of Shelf for managing data storage and retrieval

Description

1. Non compliant code

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

shelf.Response handleRequest(shelf.Request request) {
    var date = request.requestedUri.queryParameters['date'];
    var documents = getDocumentsByDate(date);
    return shelf.Response.ok(documents);
}
List getDocumentsByDate(String date) {...

The above code is vulnerable to data exposure through URL manipulation. The function `handleRequest(shelf.Request request)` is used to handle incoming requests from users. It retrieves the 'date' parameter from the URL query parameters without any form of validation. This date is then passed to the `getDocumentsByDate(String date)` function, which fetches and returns all documents sent on the specified date. This vulnerability implies that any user can manipulate the URL by changing the 'date' parameter to any date of their choice, thereby gaining access to all documents sent on that date. This exposes sensitive user information and documents to unauthorized access and potential data theft. To prevent this, it is essential to add data validation checks to ensure that only authorized users can view documents for specific dates.

2. Steps

• Validate the 'date' parameter to ensure it's in the correct format and within a reasonable range before using it in the 'getDocumentsByDate' function.

• Implement an authentication mechanism to ensure that only authorized users can access the documents.

• Use an authorization mechanism to ensure that users can only access documents that they are allowed to see.

• Consider using a rate limiting mechanism to prevent brute force attacks where an attacker might try to guess the 'date' parameter.

• Encrypt sensitive data in transit and at rest to protect it from being intercepted or accessed if the database is compromised.

3. Secure code example

import 'package:shelf/shelf.dart' as shelf;
import 'package:shelf_auth/shelf_auth.dart';
import 'package:intl/intl.dart';

shelf.Response handleRequest(shelf.Request request) {
  var date = request.requestedUri.queryParameters['date'];
  
  if (!isValidDate(date)) {...

The updated code includes a function `isValidDate` to validate the date format. It uses the `DateFormat` class from the `intl` package to parse the date string. If the date string is not in the 'yyyy-MM-dd' format, the `parseStrict` method will throw an exception, and the `isValidDate` function will return false. The `handleRequest` function now checks if the date is valid before proceeding. If the date is not valid, it returns a 403 Forbidden response. The code also includes a function `isAuthenticated` to check if the user is authenticated. This function should contain your authentication logic. The `handleRequest` function checks if the user is authenticated before proceeding. If the user is not authenticated, it returns a 403 Forbidden response. The `getDocumentsByDate` function should also include authorization checks to ensure that the user is allowed to access the requested documents. For rate limiting and data encryption, you would need to implement these at a higher level in your application or infrastructure. These are not typically implemented at the level of individual request handlers.

References

• 141. Lack of data validation - URL

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