I was just down in MD at my parents and they are also being overrun! A few Halyomorpha halys even snuck a ride to NY with me in the car, although they didn’t make it out alive… There is probably nothing attracting them per se. Because of the hot dry weather they have had a population boom and now that it is getting a little chillier they are coming inside looking for some shelter. Here is an article I found while looking for ways to discourage them.
I just fear that come winter I will land up with them swarming in bedrooms like the japanese lady bugs do. Waking up with a japanese lady bug in your mouth one morning was bad enough-a stink bug would send me over the edge!