Excessive privileges

Need

Restriction of user privileges and access control

Context

• Requirement of Ruby 2.0 or higher for running the application
• Usage of Rails framework for building web applications

Description

Non compliant code

class ApplicationController < ActionController::Base
  before_action :set_group

  def set_group
    @group = Group.find(params[:id])
  end

  def edit
    @group.update(group_params)
  end

  private

  def group_params
    params.require(:group).permit(:name, :description, :permissions)
  end
end

The above code is a simple example of a Controller in a Ruby on Rails application. This controller is handling the actions related to a Group model, which could represent a group of users in the application.

The set_group method is called before every action in the controller. It finds a group based on the id parameter passed in the request.

The edit method allows for updating the group details. It takes the parameters from the request, and updates the group with these new details. It uses the group_params method to filter the parameters that should be allowed to be updated.

The vulnerability here lies in the group_params method. This method is using Rails' Strong Parameters feature to whitelist the parameters that should be allowed for mass assignment. However, it is allowing the permissions attribute to be updated. This means that a user could potentially update the permissions of a group, thus granting excessive privileges to themselves or others.

Additionally, there is no check to ensure that the user making the request has the necessary permissions to update a group. This means that any user could potentially find the id of a group and make a request to update it.

Steps

• Implement proper authentication and authorization mechanisms to ensure that only authorized users can access the application.
• Review and update the permissions and access control mechanisms in the application to ensure that users only have the necessary privileges.
• Validate and sanitize all user input to prevent any malicious input from being executed.
• Implement proper error handling and logging mechanisms to detect and respond to any unexpected errors or exceptions.
• Regularly update and patch the application and its dependencies to address any known security vulnerabilities.
• Conduct regular security audits and penetration testing to identify and address any potential vulnerabilities.
• Educate developers and users about secure coding practices and the importance of maintaining strong security measures.

Compliant code

class ApplicationController < ActionController::Base
  before_action :set_group, :authenticate_user!, :authorize_user!

  def set_group
    @group = Group.find(params[:id])
  end

  def edit
    if @group.update(group_params)
      redirect_to @group, notice: 'Group was successfully updated.'
    else
      render :edit
    end
  end

  private

  def group_params
    params.require(:group).permit(:name, :description, :permissions)
  end

  def authenticate_user!
    # Implement your user authentication logic here
  end

  def authorize_user!
    # Implement your user authorization logic here
  end
end

The updated code includes the following changes to address the identified vulnerability:

1. Authentication and Authorization: The before_action filter now includes :authenticate_user! and :authorize_user! methods. These methods should contain the logic for authenticating and authorizing users. Only authenticated and authorized users will be able to access the application and perform actions.

2. Error Handling: The edit method now checks if the group update was successful. If it was not, it renders the edit view again. This prevents the application from crashing and potentially exposing sensitive information.

3. Input Validation: The group_params method uses strong parameters to whitelist the acceptable parameters for the group. This prevents mass assignment vulnerabilities.

4. Access Control: The authorize_user! method should contain the logic for checking if the current user has the necessary permissions to perform the action. This ensures that users can only perform actions that they have the necessary privileges for.

Remember to implement the logic for the authenticate_user! and authorize_user! methods according to your application's requirements. Regularly update and patch your application and its dependencies to address any known security vulnerabilities. Conduct regular security audits and penetration testing to identify and address any potential vulnerabilities. Educate your developers and users about secure coding practices and the importance of maintaining strong security measures.

References

• 159.Excessive privileges