This sounds a lot like my very high school-ish company and frankly, I just ignore this kind of behavior though I will say that Im one of those "I have 0 cares to give!" type of people.

If it really is important to you though, say something.

Ive worked in the same company for almost 5 years and there are a few managers and execs who will look straight at me, wont speak and who for sure dont even know my name. Granted, these people arent rude and or unprofessional enough to not respond when I say hello or something but largely they act like I dont exist when in one anothers presence.