Extract filename obfuscation into module

app/models/concerns/obfuscate_filename.rb

@@ -0,0 +1,16 @@
+module ObfuscateFilename
+  extend ActiveSupport::Concern
+
+  class_methods do
+    def obfuscate_filename(*args)
+      before_action { obfuscate_filename(*args) }
+    end
+  end
+
+  def obfuscate_filename(path)
+    file = params.dig(*path)
+    return if file.nil?
+
+    file.original_filename = "media" + File.extname(file.original_filename)
+  end
+end