This thing here, according to a new smartphone leaker in town, is the Samsung Galaxy F, Samsung's rumoured "super premium" model that takes things up a notch from the popular Galaxy S range. A quad HD display is one delight that awaits, if it's a real thing.
The images come via random Twitter account Windyleak, and show an extremely boxy case, although, in keeping with older Samsung leaks, this is almost certainly a cloaking device designed to keep the actual design of the phone more of a secret. Mr Windyleak appears to have started his account up solely to leak these Galaxy F images, saying that the 2K display is "really awesome," but not giving much more away.
Updated: Commenter mmcc09c7 pointed out that the Samsung community site @SamMobiles tweeted "The photos of the "premium Galaxy F / S" are nothing more than pictures of an early Galaxy S5 prototype. Nothing to see here." We guess time will tell.