Abstract — With the widespread use of embedded system devices, hardware designers and software developers started paying more attention to

security issues in order to protect these devices from potential threats. Physical attacks represent an important threat to these devices, and fault injection is one of the major physical attacks. However, misunderstanding the effects of the fault injection would lead to proposing either over-protections or under-protections for these devices, thus affecting the performance/cost ratio and/or the security of the device. In this article, we provide a better representation of occurring fault, as a result of clock glitch, through novel models, in order to better understand the effects of fault injection. Also, we examine their dependencies with respect to the target device and the target program. Finally, we make use of the presented fault models to break the control-flow integrity of a program by altering the value of the program counter, in order to provide an actual application example.