The rapid growth of the Industrial Internet of Things (IIoT) has brought
embedded systems into focus as major targets for both security analysts and
malicious adversaries. Due to the non-standard hardware and diverse software,
embedded devices present unique challenges to security analysts for the
accurate analysis of firmware binaries. The diversity in hardware components
and tight coupling between firmware and hardware makes it hard to perform
dynamic analysis, which must have the ability to execute firmware code in
virtualized environments. However, emulating the large expanse of hardware
peripherals makes analysts have to frequently modify the emulator for executing
various firmware code in different virtualized environments, greatly limiting
the ability of security analysis.

In this work, we explore the problem of firmware re-hosting related to the
real-time operating system (RTOS). Specifically, developers create a Board
Support Package (BSP) and develop device drivers to make that RTOS run on their
platform. By providing high-level replacements for BSP routines and device
drivers, we can make the minimal modification of the firmware that is to be
migrated from its original hardware environment into a virtualized one. We show
that an approach capable of offering the ability to execute firmware at scale
through patching firmware in an automated manner without modifying the existing
emulators. Our approach, called static binary-level porting, first identifies
the BSP and device drivers in target firmware, then patches the firmware with
pre-built BSP routines and drivers that can be adapted to the existing
emulators. Finally, we demonstrate the practicality of the proposed method on
multiple hardware platforms and firmware samples for security analysis. The
result shows that the approach is flexible enough to emulate firmware for
vulnerability assessment and exploits development.

By admin