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Insecurely generated cookies - Secure

Need​

Secure generation and transmission of cookies

Context​

  • Usage of Dart for building cross-platform mobile, web, and desktop applications
  • Usage of Shelf for managing and organizing data in a Node.js application

Description​

Non compliant code​

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

shelf.Response handleRequest(shelf.Request request) {
  var response = shelf.Response.ok('Hello, World!');
  var newResponse = response.change(headers: {'set-cookie': 'sessionId=123456; Path=/'});
  return newResponse;
}

In the above Dart code, a new cookie named sessionId is being set in the HTTP response header without the Secure attribute.

The Secure attribute is a flag that can be included in the HTTP Set-Cookie response header. This attribute directs the user agent to only include the cookie in an HTTP request if the request is transmitted over a secure channel (i.e., HTTPS).

If the Secure attribute is not set, the cookie can be transmitted over any channel, secure or non-secure. This can expose the cookie to potential security vulnerabilities, such as man-in-the-middle attacks, where an attacker intercepts the communication between the user and the server.

In this specific case, the sessionId cookie, which likely contains sensitive information, is being sent without the Secure attribute. This means that if the user's connection is not secure, the sessionId could be exposed to potential attackers.

Steps​

  • Identify all places in the code where cookies are being set.
  • For each cookie that is being set, check if the Secure attribute is being set. In this case, the Secure attribute is not being set when the 'sessionId' cookie is being created.
  • To fix the vulnerability, ensure that the Secure attribute is set for the 'sessionId' cookie. This can be done by appending '; Secure' to the Set-Cookie header.
  • The Secure attribute ensures that the cookie will only be sent over an HTTPS connection. If the application is not currently using HTTPS, it will need to be configured to do so.
  • After making these changes, thoroughly test the application to ensure that cookies are being set and sent correctly.

Compliant code​

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

shelf.Response handleRequest(shelf.Request request) {
  var response = shelf.Response.ok('Hello, World!');
  var newResponse = response.change(headers: {'set-cookie': 'sessionId=123456; Path=/; Secure'});
  return newResponse;
}

The original code was setting a cookie named 'sessionId' without the Secure attribute. This could potentially allow the cookie to be sent over an insecure connection, exposing sensitive information.

The updated code includes the Secure attribute when setting the 'sessionId' cookie. This is done by appending '; Secure' to the Set-Cookie header in the response.change() method.

var newResponse = response.change(headers: {'set-cookie': 'sessionId=123456; Path=/; Secure'});

With this change, the 'sessionId' cookie will only be sent over secure (HTTPS) connections. This helps to protect the confidentiality and integrity of the cookie, even if the connection is intercepted by an attacker.

Please note that this change requires the application to be served over HTTPS. If the application is not currently using HTTPS, it will need to be configured to do so.

After making these changes, it's important to thoroughly test the application to ensure that cookies are being set and sent correctly. This includes testing with different browsers and different network conditions.

References​

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