SafeCookies

This Gem has a middleware that will make all cookies secure. In detail, it will:

  • set all new application cookies 'HttpOnly', unless specified otherwise
  • set all new application cookies 'secure', if the request came via HTTPS and not specified otherwise
  • rewrite request cookies, setting both flags as above

Installation

Step 1

Add this line to your application's Gemfile:

gem 'safe_cookies'

Then run bundle install.

Though this gem is aimed at Rails applications, you may even use it without Rails. In that case, install it with gem install safe_cookies.

Step 2

Rails 3 and 4: add the following line in config/application.rb:

class Application < Rails::Application
  # ...
  config.middleware.insert_before ActionDispatch::Cookies, SafeCookies::Middleware
end

Rails 2: add the following lines in config/environment.rb:

Rails::Initializer.run do |config|
  # ...
  require 'safe_cookies'
  config.middleware.insert_before ActionController::Session::CookieStore, SafeCookies::Middleware
end

Step 3

Register cookies, either just after the lines you added above or in in an initializer (e.g. in config/initializers/safe_cookies.rb):

SafeCookies.configure do |config|
  config.register_cookie :remember_token, :expire_after => 1.year
  config.register_cookie :last_action, :expire_after => 30.days
  config.register_cookie :default_language, :expire_after => 10.years, :secure => false
  config.register_cookie :javascript_data, :expire_after => 1.day, :http_only => false
end

If a request has any of those four cookies, the middleware will set them anew. The remember_token and last_action cookies will be made secure and HttpOnly. Since we want to access the default language even if the user comes via HTTP, the default_language cookie is not made secure. Analogous, the javascript_data cookie will be used by a script and hence is not made HttpOnly.

Available options are: :expire_after (required), :path, :secure, :http_only.

Step 4 (important for Rails 2 only)

Override SafeCookies::Middleware#handle_unknown_cookies(cookies) to notify you e.g. by email (see "Dealing with unregistered cookies" below).

Dealing with unregistered cookies

The middleware is not able to secure cookies without knowing their attributes (most importantly: their expiry). Unfortunately, the client won't ever tell us if it stores the cookie with flags such as "secure" or which expiry date it currently has. Therefore, it is important to register all cookies that may be sent by the client, specifying their properties. Unregistered cookies cannot be secured.

If a request contains a cookie that is not registered, the middleware will raise a SafeCookies::UnknownCookieError. Rails 3+ should handle the exception as any other in your application, but by default, you will not be notified from Rails 2 applications and the user will see a standard 500 Server Error. Override SafeCookies::Middleware#handle_unknown_cookies(cookies) in the config initializer for customized exception handling (like, notifying you per email).

You should register any cookie that your application has to do with. However, there are cookies that you do not control, like Google's __utma & co. You can tell the middleware to ignore those with the config.ignore_cookie directive, which takes either a String or a Regex parameter. Be careful when using regular expressions!

In August 2013 we noticed a bug in SafeCookies < 0.1.4, by which secured cookies would be set for the current "directory" (see comments in cookie_path_fix.rb) instead of root (which usually is what you want). Users would get multiple cookies for that domain, leading to issues like being unable to sign in.

The configuration option config.fix_paths turns on fixing this error. It requires an option :for_cookies_secured_before => Time.parse('some minutes after you will have deployed') which reflects the point of time from which cookies will be secured with the correct path. The middleware will fix the cookie paths by rewriting all cookies that it has already secured, but only if the were secured before the time you specified.

Development

  • Tests live in spec.
  • You can run specs from the project root by saying bundle exec rake.

If you would like to contribute:

  • Fork the repository.
  • Push your changes with passing specs.
  • Send us a pull request.