Proof-of-concept: reCAPTCHA at sign-in

app/components/captcha_submit_button_component.html.erb

@@ -32,6 +32,7 @@
         type: :submit,
         big: true,
         wide: true,
+        **button_options,
       ).with_content(content) %>
   <% if recaptcha_script_src.present? %>
     <%= content_tag(:script, '', src: recaptcha_script_src, async: true) %>

app/components/captcha_submit_button_component.rb

@@ -1,14 +1,15 @@
 # frozen_string_literal: true
 
 class CaptchaSubmitButtonComponent < BaseComponent
-  attr_reader :form, :action, :tag_options
+  attr_reader :form, :action, :button_options, :tag_options
 
   alias_method :f, :form
 
   # @param [String] action https://developers.google.com/recaptcha/docs/v3#actions
-  def initialize(form:, action:, **tag_options)
+  def initialize(form:, action:, button_options:, **tag_options)
     @form = form
     @action = action
+    @button_options = button_options
     @tag_options = tag_options
   end
 

app/controllers/users/sessions_controller.rb

@@ -31,6 +31,7 @@ def create
       session[:sign_in_flow] = :sign_in
       return process_locked_out_session if session_bad_password_count_max_exceeded?
       return process_locked_out_user if current_user && user_locked_out?(current_user)
+      return process_failed_captcha if !valid_captcha_result?
 
       rate_limit_password_failure = true
       self.resource = warden.authenticate!(auth_options)
@@ -79,6 +80,40 @@ def process_locked_out_session
       redirect_to root_url
     end
 
+    def valid_captcha_result?
+      if cookies[:device] && (device = Device.find_by(cookie_uuid: cookies[:device]))
+        return true if device.user.email_addresses.lazy.map(&:email).include?(auth_params[:email])
+      end
+
+      response, _assessment_id = recaptcha_form.submit(params.require(:user)[:recaptcha_token])
+      flash[:error] = response.first_error_message if !response.success?
+      response.success?
+    end
+
+    def process_failed_captcha
+      warden.logout(:user)
+      warden.lock!
+      redirect_to root_url
+    end
+
+    def recaptcha_form
+      @recaptcha_form ||= SignInRecaptchaForm.new(**recaptcha_form_args)
+    end
+
+    def recaptcha_form_args
+      args = { analytics: }
+      if IdentityConfig.store.phone_recaptcha_mock_validator
+        args.merge(
+          form_class: RecaptchaMockForm,
+          score: params.require(:user)[:recaptcha_mock_score].to_f,
+        )
+      elsif FeatureManagement.recaptcha_enterprise?
+        args.merge(form_class: RecaptchaEnterpriseForm)
+      else
+        args
+      end
+    end
+
     def redirect_to_signin
       controller_info = 'users/sessions#create'
       analytics.invalid_authenticity_token(controller: controller_info)

app/forms/sign_in_recaptcha_form.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+class SignInRecaptchaForm
+  RECAPTCHA_ACTION = 'sign_in'
+
+  attr_reader :form_class, :form_args
+
+  delegate :submit, :errors, to: :form
+
+  def initialize(form_class: RecaptchaForm, **form_args)
+    @form_class = form_class
+    @form_args = form_args
+  end
+
+  private
+
+  def form
+    @form ||= form_class.new(
+      score_threshold: IdentityConfig.store.sign_in_recaptcha_score_threshold,
+      recaptcha_action: RECAPTCHA_ACTION,
+      **form_args,
+    )
+  end
+end

app/views/devise/sessions/new.html.erb

@@ -48,7 +48,12 @@
         },
       ) %>
   <%= hidden_field_tag :platform_authenticator_available, id: 'platform_authenticator_available' %>
-  <%= f.submit t('links.sign_in'), full_width: true, wide: false %>
+
+  <%= render CaptchaSubmitButtonComponent.new(
+        form: f,
+        action: SignInRecaptchaForm::RECAPTCHA_ACTION,
+        button_options: { full_width: true },
+      ).with_content(t('links.sign_in')) %>
 <% end %>
 <% if desktop_device? %>
   <div class='margin-x-neg-1 margin-top-205'>

config/application.yml.default

@@ -316,6 +316,7 @@ session_timeout_in_minutes: 15
 session_timeout_warning_seconds: 150
 session_total_duration_timeout_in_minutes: 720
 ses_configuration_set_name: ''
+sign_in_recaptcha_score_threshold: 0.0
 sp_handoff_bounce_max_seconds: 2
 show_unsupported_passkey_platform_authentication_setup: false
 show_user_attribute_deprecation_warnings: false
@@ -431,6 +432,7 @@ development:
   secret_key_base: development_secret_key_base
   session_encryption_key: 27bad3c25711099429c1afdfd1890910f3b59f5a4faec1c85e945cb8b02b02f261ba501d99cfbb4fab394e0102de6fecf8ffe260f322f610db3e96b2a775c120
   show_unsupported_passkey_platform_authentication_setup: true
+  sign_in_recaptcha_score_threshold: 0.3
   skip_encryption_allowed_list: '["urn:gov:gsa:SAML:2.0.profiles:sp:sso:localhost"]'
   state_tracking_enabled: true
   telephony_adapter: test

lib/identity_config.rb

@@ -385,6 +385,7 @@ def self.store
     config.add(:show_user_attribute_deprecation_warnings, type: :boolean)
     config.add(:short_term_phone_otp_max_attempts, type: :integer)
     config.add(:short_term_phone_otp_max_attempt_window_in_seconds, type: :integer)
+    config.add(:sign_in_recaptcha_score_threshold, type: :float)
     config.add(:skip_encryption_allowed_list, type: :json)
     config.add(:sp_handoff_bounce_max_seconds, type: :integer)
     config.add(:sp_issuer_user_counts_report_configs, type: :json)