In T2 they were in a special room inside the duty free shop with a door to enter and nothing visible from the outside.

Plus, you won't be able to tell easily that they are Marlboro's as the entire carton (and as it turns out each packet) are obscured or plastered with pictures of diseases smoking can cause. So better ask the shop assistant for help to identify your preferred poison (literally).

I don't smoke myself, but was asked to bring some for someone in Europe as cigarettes are expensive there as well and I was quite confused at first by most cartons looking the same from afar .