added config.active_record.whitelist_attributes which creates an empty whitelist of attributes available for mass assignment for all models in your app

activerecord/lib/active_record/railtie.rb

@@ -50,6 +50,9 @@ module ActiveRecord
 
     initializer "active_record.set_configs" do |app|
       ActiveSupport.on_load(:active_record) do
+        if app.config.active_record.delete(:whitelist_attributes)
+          attr_accessible(nil)
+        end
         app.config.active_record.each do |k,v|
           send "#{k}=", v
         end

railties/guides/source/configuring.textile

@@ -229,6 +229,8 @@ h4. Configuring Active Record
 
 * +config.active_record.lock_optimistically+ controls whether ActiveRecord will use optimistic locking. By default this is +true+.
 
+* +config.active_record.whitelist_attributes+ will create an empty whitelist of attributes available for mass-assignment security for all models in your app.
+
 The MySQL adapter adds one additional configuration option:
 
 * +ActiveRecord::ConnectionAdapters::MysqlAdapter.emulate_booleans+ controls whether ActiveRecord will consider all +tinyint(1)+ columns in a MySQL database to be booleans. By default this is +true+.

railties/guides/source/security.textile

@@ -459,13 +459,13 @@ When assigning attributes in Active Record using +new+, +attributes=+, or +updat
 @user.is_admin # => true
 </ruby>
 
-A more paranoid technique to protect your whole project would be to enforce that all models whitelist their accessible attributes.  This can be easily achieved with a very simple initializer:
+A more paranoid technique to protect your whole project would be to enforce that all models define their accessible attributes.  This can be easily achieved with a very simple application config option of:
 
 <ruby>
-ActiveRecord::Base.send(:attr_accessible, nil)
+config.active_record.whitelist_attributes = true
 </ruby>
 
-This will create an empty whitelist of attributes available for mass assignment for all models in your app. As such, your models will need to explicitly whitelist accessible parameters by using an +attr_accessible+ declaration. This technique is best applied at the start of a new project. However, for an existing project with a thorough set of functional tests, it should be straightforward and relatively quick to insert this initializer, run your tests, and expose each attribute (via +attr_accessible+) as dictated by your failing tests.
+This will create an empty whitelist of attributes available for mass-assignment for all models in your app. As such, your models will need to explicitly whitelist or blacklist accessible parameters by using an +attr_accessible+ or +attr_protected+ declaration.  This technique is best applied at the start of a new project. However, for an existing project with a thorough set of functional tests, it should be straightforward and relatively quick to use this application config option; run your tests, and expose each attribute (via +attr_accessible+ or +attr_protected+) as dictated by your failing tests.
 
 h3. User Management
 

railties/test/application/configuration_test.rb

@@ -258,6 +258,18 @@ module ApplicationTests
       assert_equal res, last_response.body # value should be unchanged
     end
 
+    test "sets all Active Record models to whitelist all attributes by default" do
+      add_to_config <<-RUBY
+        config.active_record.whitelist_attributes = true
+      RUBY
+
+      require "#{app_path}/config/environment"
+
+      assert_equal ActiveModel::MassAssignmentSecurity::WhiteList,
+                   ActiveRecord::Base.active_authorizers[:default].class
+      assert_equal [""], ActiveRecord::Base.active_authorizers[:default].to_a
+    end
+
     test "registers interceptors with ActionMailer" do
       add_to_config <<-RUBY
         config.action_mailer.interceptors = MyMailInterceptor