Industry 4.0 advent opens several cyber-threats scenarios originally designed for classic information technology, drawing the attention to serious risks for the modern industrial control networks. To cope with this problem, in this paper we address the security issues related to covert channels applied to industrial networks, identifying the new vulnerability points when information technologies converge with operational technologies such as edge computing infrastructures. Specifically, we define two signaling strategies where we exploit the ModbusTCP protocol as target to set up a covert channel. Once the threat channel is established, passive and active offensive methodologies are further exploited by implementing and testing them on a real Industrial Internet of Things testbed. The experimental results highlight the potential damage of such specific threats and the easy extrapolation of the attacks to other types of channels in order to show the new risks for the Industry 4.0. Related to this, we discuss some countermeasures offering an overview of possible mitigation and defensive measures.
