NEW YORK (AP) — Burger King pulled a pretty juicy marketing stunt last month that drew plenty of attention — not just to the Whopper, but also to the intrinsic vulnerabilities of a new type of voice-activated gadget.

The fast food chain's 15-second television ad targeted Google Home, a speaker that can answer questions and control other smart appliances. When an actor in the ad said "OK, Google" and asked a question about the Whopper, Google Home obediently began reading the burger's ingredients in homes around the country — effectively extending the commercial for however long it took someone...