/usr/lib/ruby/vendor_ruby/active_record/attribute_methods/ is in ruby-activerecord-3.2 3.2.16-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/active_record/attribute_methods/before_type_cast.rb
/usr/lib/ruby/vendor_ruby/active_record/attribute_methods/deprecated_underscore_read.rb
/usr/lib/ruby/vendor_ruby/active_record/attribute_methods/dirty.rb
/usr/lib/ruby/vendor_ruby/active_record/attribute_methods/primary_key.rb
/usr/lib/ruby/vendor_ruby/active_record/attribute_methods/query.rb
/usr/lib/ruby/vendor_ruby/active_record/attribute_methods/read.rb
/usr/lib/ruby/vendor_ruby/active_record/attribute_methods/serialization.rb
/usr/lib/ruby/vendor_ruby/active_record/attribute_methods/time_zone_conversion.rb
/usr/lib/ruby/vendor_ruby/active_record/attribute_methods/write.rb