The purpose of the paper is to analyze the vulnerabilities of Critical Energy Infrastructures' systems in the event of cyber-attack. The global tendency of cyber-attacks puts Critical Energy Infrastructures on one of the first places for targets. Critical Infrastructure Protection (CIP) has become an increasingly relevant topic in the global industrial environment, as the consequences of cyber-attacks toward ICS can result in physical disruption and loss of human lives. The analysis presented in the paper will take into consideration three different case scenarios of cyber-attacks to Critical Energy Infrastructures, and will evaluate the outcomes and the tactics used by the organizations' response and recovery.