To be more specific, in this patent application they talk about awarding trophies using disk access "triggers".
You can get a general idea of how it works below.
United States Patent Application 2013007355
Title: METHOD AND APPARATUS FOR AWARDING TROPHIES
A method and apparatus for adding trophy support games that do not have trophies without modifying the original game. The method and apparatus are used to detect particular disk access, use the detected disk access as potential trophy triggers in games, and recognize the triggers while a game is played. Trophies are awarded based on the triggers, and the awarded trophies are stored.
Headed to PS4?
lOck/mOck IF Old