The continuous growth of cyber security threats and attacks including the increasing sophistication of malware is impacting the security of critical infrastructure, industrial control systems, and Supervisory Control and Data Acquisition (SCADA) control systems. The reliable operation of modern infrastructures depends on computerized systems and SCADA systems. Since the emergence of Internet and World Wide Web technologies, these systems were integrated with business systems and became more exposed to cyber threats. There is a growing concern about the security and safety of the SCADA control systems. The Presidential Decision Directive 63 document established the framework to protect the critical infrastructure and the Presidential document of 2003, the National Strategy to Secure Cyberspace stated that securing SCADA systems is a national priority. The critical infrastructure includes telecommunication, transportation, energy, banking, finance, water supply, emergency services, government services, agriculture, and other fundamental systems and services that are critical to the security, economic prosperity, and social well-being of the public. The critical infrastructure is characterized by interdependencies (physical, cyber, geographic, and logical) and complexity (collections of interacting components). Therefore, information security management principles and processes need to be applied to SCADA systems without exception. Critical infrastructure disruptions can directly and indirectly affect other infrastructures, impact large geographic regions, and send ripples throughout the national and global economy. For example, under normal operating conditions, the electric power infrastructure requires fuels (natural gas and petroleum), transportation, water, banking and finance, telecommunication, and SCADA systems for monitoring and control.