Fields like created_at, updated_at or cartodb_id are a greyed out thus not allowing us to add it to the info window. Is there a way to extract the data from default fields in cartodb?
One pretty easy way to add this, is by selecting those fields with a SQL query, and give them aliases so you can select them field on the infowindow configurator. Here is a sample SQL query that would do that
SELECT cartodb_id, the_geomwebmercator, created_at as date FROM table_name.