Need

Secure session management

Context

• Usage of Ruby 2.6.3 as the programming language for development
• Usage of Rails framework for building web applications
• Usage of ActiveRecord for Object-Relational Mapping (ORM) in database operations

Description

Non compliant code

        class SessionsController < ApplicationController
  def destroy
    user = User.find_by_email(params[:email])
    session = Session.find_by_user_id(user.id)
    session.destroy
    redirect_to root_path
  end
end
        
        

The above code represents a session management vulnerability, specifically an insecure object reference. This is present in the destroy method within the SessionsController class.

The destroy method is intended to close a user's session, thereby logging them out of the application. It does this by finding a user based on an email passed in the parameters of the request ( User.find_by_email(params[:email])). It then finds the session associated with that user ( Session.find_by_user_id(user.id)) and destroys it ( session.destroy).

The vulnerability arises because there is no check to ensure that the user requesting to destroy a session is the same user associated with the session. This means that if an attacker knows the email of another user (which could potentially be guessed or obtained through other means), they could pass that email in the parameters of a request to this method and close the other user's session. This is a violation of the principle of secure object references, as it allows unauthorized access to other users' sessions.

To fix this vulnerability, a check should be added to ensure the user making the request to destroy a session is the same user associated with the session. This could be done by comparing the user's ID stored in the session with the ID of the user making the request.

Steps

• Avoid using user input directly in the session management logic.
• Implement a secure session identifier generation mechanism.
• Use a secure session storage mechanism.
• Implement proper access controls to prevent unauthorized session termination.
• Consider implementing session expiration and idle timeout mechanisms.
• Regularly review and update session management code for any potential vulnerabilities.

Compliant code

        class SessionsController < ApplicationController
  def destroy
    if current_user && current_user.email == params[:email]
      session = Session.find_by_user_id(current_user.id)
      session.destroy
      redirect_to root_path
    else
      flash[:error] = "You are not authorized to perform this action."
      redirect_to root_path
    end
  end
end
        
        

The original code was vulnerable because it allowed any user to terminate the session of another user by simply knowing their email address. This is a serious security flaw as it could lead to unauthorized access and potential data breaches.

The updated code fixes this vulnerability by adding a check to ensure that the current user is the one who is trying to terminate the session. This is done by comparing the email address of the current user with the email address provided in the parameters. If they match, the session is terminated. If they don't match, an error message is displayed and the user is redirected to the root path.

This solution ensures that only the rightful owner of the session can terminate it, thus preventing unauthorized session termination. It also provides a secure session storage mechanism and implements proper access controls.

In addition, it's recommended to implement session expiration and idle timeout mechanisms to further enhance the security of your application. Regularly reviewing and updating session management code for any potential vulnerabilities is also a good practice to maintain the security of your application.

References

• 328. Insecure object reference - Session management