/usr/lib/ruby/vendor_ruby/active_record/mass_assignment_security/ is in ruby-protected-attributes 1.1.3-2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/active_record/mass_assignment_security/associations.rb
/usr/lib/ruby/vendor_ruby/active_record/mass_assignment_security/attribute_assignment.rb
/usr/lib/ruby/vendor_ruby/active_record/mass_assignment_security/core.rb
/usr/lib/ruby/vendor_ruby/active_record/mass_assignment_security/inheritance.rb
/usr/lib/ruby/vendor_ruby/active_record/mass_assignment_security/nested_attributes.rb
/usr/lib/ruby/vendor_ruby/active_record/mass_assignment_security/persistence.rb
/usr/lib/ruby/vendor_ruby/active_record/mass_assignment_security/reflection.rb
/usr/lib/ruby/vendor_ruby/active_record/mass_assignment_security/relation.rb
/usr/lib/ruby/vendor_ruby/active_record/mass_assignment_security/validations.rb