The production processes of critical infrastructures (CIs) are managed and monitored by Industrial Control Systems (ICS) such as SCADA (Supervisory Control and Data Acquisition). The resulting CIs networks are huge and complex, which have inadvertently called for the integration of other technologies such as the internet for efficiency. The integration of such unsecured technologies and the advent of new computing paradigms such as IoT (internet of things) and Cloud computing which are being integrated into current industrial environments, giving rise to Industry 4.0 have further expanded the attack surface. This chapter considers a new breed of security attacks, crypto-viral attacks (crypto mining and crypto ransomware attacks), which target both the production and control networks of CIs. The authors model these attacks and evaluate their impacts. Such modeling is crucial in understanding the extent of the scope and detection capabilities of the first line of defense (intrusion detection and prevention systems), and possible avenues for mitigation strategies are suggested.