HDMI firewall

Any device sporting a chip and some form of communications protocol can be hacked – that’s almost as strong a law as those governing gravity.

Besides audio and video data, there are a number of parallel protocols in HDMI that transmit more information than we’d expect.

There is I2C configuration data, HDCP (High-bandwidth Digital Content Protection) DRM (Digital Rights Management) encryption data, HPD (Hot-Plug Detection) and CEC (Consumer Electronics Control) – just to name a few.

Is it time for an HDMI firewall? [King Kévin] thinks so, because he’s made one. It’s a surprisingly simple device, because the non-signal capabilities of HDMI rely on a set of conductors which are simply not connected. This of course also disconnects the on-board EEPROM in the device being connected, so there’s an EEPROM on the firewall board to replace it which must be programmed with the information for the device in question.

The HDMI firewall is little more than a physical dongle that can be directly connected to the HDMI port you want to secure. It works by blocking all data that’s not related to video and audio streaming. One dongle is required per port to be protected.

HDMI Firewall Protects Your Display Port (but Not your DisplayPort)
A dongle can keep your HDMI ports, and your network, safe.
https://www.tomshardware.com/news/hdmi-firewall-dongle-protects-unexpected-attack-vector

HDMI IS AN ATTACK SURFACE, SO HERE’S AN HDMI FIREWALL
https://hackaday.com/2022/06/22/hdmi-is-an-attack-surface-so-heres-an-hdmi-firewall/

https://git.cuvoodoo.info/kingkevin/board/src/branch/hdmi_firewall