  Physically accessible devices such as sensor nodes in Wireless Sensor
Networks or "smart" devices in the Internet of Things have to be resistant to a
broad spectrum of physical attacks, for example to Side Channel Analysis and to
Fault Injection attacks. In this work we concentrate on the vulnerability of
ASICs to precise optical Fault Injection attacks. Here we propose to use metal
fillers as potential low-cost countermeasure that may be effective against a
broad spectrum of physical attacks. In our future work we plan to evaluate
different methods of metal fillers placement, to select an effective one and to
integrate it as additional design rules into automated design flows.
