High-Def Fuzzing: Exploring Vulnerabilities in HDMI-CEC presented at Defcon 2015

by Joshua Smith,

Summary : The HDMI (High Definition Multimedia Interface) standard has gained extensive market penetration. Nearly every piece of modern home theater equipment has HDMI support and most modern mobile devices actually have HDMI-capable outputs, though it may not be obvious. Lurking inside most modern HDMI-compatible devices is something called HDMI-CEC, or Consumer Electronics Control. This is the functionality that allows a media device to, for example, turn on your TV and change the TV’s input. That doesn’t sound interesting, but as we'll see in this presentation, there are some very surprising things an attacker can do by exploiting CEC software implementations. Then there's something called HEC or HDMI Ethernet Connection, which allows devices to establish an Ethernet connection of up to 100Mbit/s over their HDMI connections (newer HDMI standards raise the speed to 1Gbit/s).
Don't think your mobile phone implements CEC? You might be wrong. Most modern Android-based phones and tablets have a Slimport(r) connection that supports HDMI-CEC. Ever heard of MHL (Mobile High-Definition Link)? Think Samsung and HTC (among other) mobile devices, and many JVC, Kenwood, Panasonic, and Sony car stereos – as many as 750 million devices in the world so far. Guess what? MHL supports HDMI-CEC as well. Let's explore, and own, this attack space.
Kernelsmith is senior vulnerability researcher with Hewlett-Packard Security Research (HPSR). In this role, he analyzes and performs root-cause analysis on hundreds of vulnerabilities submitted to the Zero-Day Initiative (ZDI) program, which represents the world’s largest vendor-agnostic bug bounty program. His focus includes analyzing and performing root-cause analysis on hundreds of zero-day vulnerabilities submitted by ZDI researchers from around the world. Joshua is also a developer for the Metasploit Framework and has spoken at a few conferences and holds a few certifications.
Prior to joining HP, Smith served in the U.S. Air Force in various roles including as an Intercontinental Ballistic Missile (ICBM) Crew Commander and Instructor, but more relevantly as a penetration tester for the 92d Information Warfare Aggressor Squadron. Post-military, he became a security engineer at the John Hopkins University Applied Physics Lab, where he began contributing to the Metasploit Framework. Smith performed research into weapons systems vulnerabilities as well as evasion and obfuscation techniques to add depth and realism to security device tests. Smith received a B.S. in Aeronautical Engineering from Rensselaer Polytechnic Institute and an M.A. in Management of Information Systems from the University of Great Falls.