“Lockpicking in the IoT, …or why adding BTLE to a device sometimes isn’t smart at all” by Ray was one of my favourite talks, as it beautifully showed many different attack vectors as well as giving a nice guide for getting started in this area.
It impressed me how carefree vendors and startups handled hardware and software security in “smart” devices as it seems that their devices were more or less easy to own. In his talk Ray pointed out physical AND implementational weaknesses that remained even after he reported them to the vendors.
The most prominent sample he gave was when he opened a “Masterlock” by spinning a magnet on the lock itself to open it.