Devise::PwnedPassword

Devise extension that checks user passwords against the PwnedPasswords dataset (https://haveibeenpwned.com/Passwords).

Checks for compromised ("pwned") passwords in 2 different places/ways:

1. As a standard model validation using pwned. This:
   • prevents new users from being created (signing up) with a compromised password
   • prevents existing users from changing their password to a password that is known to be compromised
2. (Optionally) Whenever a user signs in, checks if their current password is compromised and shows a warning if it is.

Based on devise-uncommon_password.

Recently the HaveIBeenPwned API has moved to an authenticated/paid model, but this does not affect the PwnedPasswords API; no payment or authentication is required.

Usage

Add the :pwned_password module to your existing Devise model.

class AdminUser < ApplicationRecord
  devise :database_authenticatable,
         :recoverable, :rememberable, :trackable, :validatable, :pwned_password
end

Users will receive the following error message if they use a password from the PwnedPasswords dataset:

Password has previously appeared in a data breach and should never be used. Please choose something harder to guess.

Configuration

You can customize this error message by modifying the devise YAML file.

# config/locales/devise.en.yml
en:
  errors:
    messages:
      pwned_password: "has previously appeared in a data breach and should never be used. If you've ever used it anywhere before, change it immediately!"

By default passwords are rejected if they appear at all in the data set. Optionally, you can add the following snippet to config/initializers/devise.rb if you want the error message to be displayed only when the password is present a certain number of times in the data set:

# Minimum number of times a pwned password must exist in the data set in order
# to be reject.
config.min_password_matches = 10

By default responses from the PwnedPasswords API are timed out after 5 seconds to reduce potential latency problems. Optionally, you can add the following snippet to config/initializers/devise.rb to control the timeout settings:

config.pwned_password_open_timeout = 1
config.pwned_password_read_timeout = 2

How to warn existing users when they sign in

You can optionally warn existing users when they sign in if they are using a password from the PwnedPasswords dataset.

To enable this, you must override after_sign_in_path_for, like this:

# app/controllers/application_controller.rb

  def after_sign_in_path_for(resource)
    set_flash_message! :alert, :warn_pwned if resource.respond_to?(:pwned?) && resource.pwned?
    super
  end

For an Active Admin application the following monkey patch is needed:

# config/initializers/active_admin_devise_sessions_controller.rb
class ActiveAdmin::Devise::SessionsController
  def after_sign_in_path_for(resource)
    set_flash_message! :alert, :warn_pwned if resource.respond_to?(:pwned?) && resource.pwned?
    super
  end
end

To prevent the default call to the HaveIBeenPwned API on user sign-in (only really useful if you're going to check pwned? after sign-in as used above), add the following to config/initializers/devise.rb:

config.pwned_password_check_on_sign_in = false

Customize warning message

The default message is:

Your password has previously appeared in a data breach and should never be used. We strongly recommend you change your password.

You can customize this message by modifying the devise.en.yml locale file.

# config/locales/devise.en.yml
en:
  devise:
    sessions:
      warn_pwned: "Your password has previously appeared in a data breach and should never be used. We strongly recommend you change your password everywhere you have used it."

Customize the warning threshold

By default the same value, config.min_password_matches is used as the threshold for rejecting a passwords for new user sign-ups and for warning existing users.

If you want to use different thresholds for rejecting the password and warning the user (for example you may only want to reject passwords that are common but warn if the password occurs at all in the list), you can set a different value for each.

To change the threshold used for the warning only, add to config/initializers/devise.rb

# Minimum number of times a pwned password must exist in the data set in order
# to warn the user.
config.min_password_matches_warn = 1

Note: If you do have a different warning threshold, that threshold will also be used when a user changes their password (added as an error!) so that they don't continue to be warned if they choose another password that is in the pwned list but occurs with a frequency below the main threshold that is used for new user registrations (config.min_password_matches).

Disabling in test environments

Currently this module cannot be mocked out for test environments. Because an API call is made this can slow down tests, or make test fixtures needlessly complex (dynamically generated passwords). The module can be disabled in test environments like this.

class User < ApplicationRecord
  devise :invitable ...  :validatable, :lockable
  devise :pwned_password unless Rails.env.test?
end

Installation

Add this line to your application's Gemfile:

gem 'devise-pwned_password'

And then execute:

$ bundle install

Considerations

A few things to consider/understand when using this gem:

• User passwords are hashed using SHA-1 and then truncated to 5 characters, implementing the k-Anonymity model described in https://haveibeenpwned.com/API/v2#SearchingPwnedPasswordsByRange Neither the clear-text password nor the full password hash is ever transmitted to a third party. More implementation details and important caveats can be found in https://blog.cloudflare.com/validating-leaked-passwords-with-k-anonymity/

• This puts an external API in the request path of users signing up to your application. This could potentially add some latency to this operation. The gem is designed to silently swallows errors if the PwnedPasswords service is unavailable, allowing users to use compromised passwords during the time when it is unavailable.

Contributing

To contribute:

• Check the issue tracker and pull requests for anything similar
• Fork the repository
• Make your changes
• Run bin/test to make sure the unit tests still run
• Send a pull request

License

The gem is available as open source under the terms of the MIT License.