A7 Missing Function Level Access Control (Admin Controller)

Description

Many web applications check URL access rights before rendering protected links and buttons. However, applications need to perform similar access control checks each time these pages are accessed, or attackers will be able to forge URLs to access these hidden pages anyway.

Bug

Rails provides the ability to apply before_filter(s) which run prior to rendering content to the user. This is helpful when restricting access to content based on the user's role. These filters can be skipped on certain actions or controllers and entirely if certain conditions are met. In this case, the before_filter is being skipped if the admin_id param is equal to 1.

class AdminController < ApplicationController

  before_filter :administrative, :if => :admin_param
  
  ...
  
  def admin_param
    params[:id] != '1'
  end

Solution

Failure to Restrict URL Access - ATTACK

Request the following URL: /admin/1/dashboard and have fun :-)

Failure to Restrict URL Access - SOLUTION

The code is already available to restrict access to the admin controller by role within app/controllers/application_controller.rb. The additional condition that if the admin_id param equals 1 means the filter can be circumvented by an attacker. The way to fix this issue is to remove the conditional and enforce the filter on all access requests to the admin dashboard as follows:

class AdminController < ApplicationController

  before_filter :administrative

Hint

I bet there is some admin functionality in here :-)