During lunchtime, I watched as a friend attempted to discreetly turn on a television in a public place and flip through the channels using his phone's infrared transmitter (although rather stupidly, since the television was not actually connected by coaxial to a source).
Although he was not caught, I wondered if there was any way to prevent such attacks if a television or projector was used in a large venue. Taking control simply by looking at the brand and model is a serious vulnerability: anyone with widely available hardware and software can mute audio, turn off a projector, change inputs (such as with a network projector, in preparation to take video control of it as well), and the like. The vulnerability is also present in common set-top boxes (which can be used to, for instance, change the channels at a sports bar).
Are there any practical remedies to this problem? Taping the IR receiver on the devices prevents legitimate use of a remote control, and devices that already use IR cannot simply be retrofitted with RF.