  Wireless communication standards and implementations have a troubled history
regarding security. Since most implementations and firmwares are closed-source,
fuzzing remains one of the main methods to uncover Remote Code Execution (RCE)
vulnerabilities in deployed systems. Generic over-the-air fuzzing suffers from
several shortcomings, such as constrained speed, limited repeatability, and
restricted ability to debug. In this paper, we present Frankenstein, a fuzzing
framework based on advanced firmware emulation, which addresses these
shortcomings. Frankenstein brings firmware dumps "back to life", and provides
fuzzed input to the chip's virtual modem. The speed-up of our new fuzzing
method is sufficient to maintain interoperability with the attached operating
system, hence triggering realistic full-stack behavior. We demonstrate the
potential of Frankenstein by finding three zero-click vulnerabilities in the
Broadcom and Cypress Bluetooth stack, which is used in most Apple devices, many
Samsung smartphones, the Raspberry Pis, and many others.
  Given RCE on a Bluetooth chip, attackers may escalate their privileges beyond
the chip's boundary. We uncover a Wi-Fi/Bluetooth coexistence issue that
crashes multiple operating system kernels and a design flaw in the Bluetooth
5.2 specification that allows link key extraction from the host. Turning off
Bluetooth will not fully disable the chip, making it hard to defend against RCE
attacks. Moreover, when testing our chip-based vulnerabilities on those
devices, we find BlueFrag, a chip-independent Android RCE.
