Plot (no spoilers): a bunch of friends go to a party on a girlfriend apartment. They start to talk about the house, rented, and about a sort of attic. The ultimately go to the attic and strange things start to happen. Possessions and such. I do not remember the title and I think it was a french movie. I saw it five or more years ago. Thanks.
The Possession of David O’Reilly (2010) (AKA The Torment)?
Hi. After posting I continued searching and finally I found it; it was «Prying Eyes». Solved.
Thanks for letting us know tipar!