  Voltage Fault Injection (VFI), also known as power glitching, has proven to
be a severe threat to real-world systems. In VFI attacks, the adversary
disturbs the power-supply of the target-device forcing the device to
illegitimate behavior. Various countermeasures have been proposed to address
different types of fault injection attacks at different abstraction layers,
either requiring to modify the underlying hardware or software/firmware at the
machine instruction level. Moreover, only recently, individual chip
manufacturers have started to respond to this threat by integrating
countermeasures in their products. Generally, these countermeasures aim at
protecting against single fault injection (SFI) attacks, since Multiple Fault
Injection (MFI) is believed to be challenging and sometimes even impractical.
In this paper, we present {\mu}-Glitch, the first Voltage Fault Injection (VFI)
platform which is capable of injecting multiple, coordinated voltage faults
into a target device, requiring only a single trigger signal. We provide a
novel flow for Multiple Voltage Fault Injection (MVFI) attacks to significantly
reduce the search complexity for fault parameters, as the search space
increases exponentially with each additional fault injection. We evaluate and
showcase the effectiveness and practicality of our attack platform on four
real-world chips, featuring TrustZone-M: The first two have interdependent
backchecking mechanisms, while the second two have additionally integrated
countermeasures against fault injection. Our evaluation revealed that
{\mu}-Glitch can successfully inject four consecutive faults within an average
time of one day. Finally, we discuss potential countermeasures to mitigate VFI
attacks and additionally propose two novel attack scenarios for MVFI.
