Hiding Hardware Trojan Communication Channels in Partially Specified SoC Bus Functionality

  • Authors:
    Nicole Fern (UC/Santa Barbara), Ismail San (UC/Santa Barbara), Cetin Koc (UC/Santa Barbara), K.T. Tim Cheng (UC/Santa Barbara)
    Publication ID:
    P091211
    Publication Type:
    Paper
    Received Date:
    30-Jun-2017
    Last Edit Date:
    30-Jun-2017
    Research:
    2634.001 (University of California/Santa Barbara)

Abstract

On-chip bus implementations must be bug-free and secure to provide the functionality and performance required by modern SoC designs. Regardless of the specific topology and protocol, bus behavior is never fully specified, meaning there exist cycles/conditions where some bus signals are irrelevant, and ignored by the verification effort. We highlight the susceptibility of current bus implementations to Hardware Trojans hiding in this partially specified behavior, and present a model for creating a covert Trojan communication channel between SoC components for any bus topology and protocol. By only altering existing bus signals during the period where their behaviors are unspecified, the Trojan channel is very difficult to detect. We give Trojan channel circuitry specifics for AMBA AXI4 and APB, then create a simple system comprised of several master and slave units connected by an AXI4-Lite interconnect to quantify the overhead of the Trojan channel and illustrate the ability of our Trojans to evade a suite of protocol compliance checking assertions from ARM. We also create an SoC design running a multi-user Linux OS to demonstrate how a Trojan communication channel can allow an unprivileged user access to root-user data. We then outline several detection strategies for this class of hardware Trojan.

4819 Emperor Blvd, Suite 300 Durham, NC 27703 Voice: (919) 941-9400 Fax: (919) 941-9450

Important Information for the SRC website. This site uses cookies to store information on your computer. By continuing to use our site, you consent to our cookies. If you are not happy with the use of these cookies, please review our Cookie Policy to learn how they can be disabled. By disabling cookies, some features of the site will not work.