In a presentation to the European Broadcasting Union (EBU), Rafael Scheel (Senior Penetration Tester & Security Researcher at Oneconsult AG) gives an introduction to IoT cyber security and shows in a live hacking demo an attack which allows to remotely takeover bulks of smart TVs over the TV stream signal. About 90% of the TVs sold in the last years are potential victims of similar attacks.
UPDATE: The DVB Steering Board has approved updates to the technical specifications to prevent man-in-the-middle attacks. Links to the press release and updated spec (BlueBook A137 / TS 102 809):