The SCADA systems evolved from static to dynamic systems. The increased connectivity to internet and mobile device technology has also a major impact on control system architectures. Standardization and use of open market technologies are current requirements in control systems. Modern products are often based on component architectures using commercial off the shelf products (COTS) elements as units. This architecture leads to control systems that are becoming very complex software applications with the following characteristics:
• Time critical
• Fault tolerant
SCADA systems are exposed to the same cyberspace threats as any business system because they share the common vulnerabilities with the traditional information technology systems. Also most SCADA systems are not protected with appropriate security safeguards. The operating personnel are lacking the security training and awareness. Threats against SCADA systems are ranked high in the list of government concerns, since terrorists have threatened to attack several SCADA systems of critical infrastructure and successfully launch near disastrous attacks.
In addition, recent attacks are becoming more sophisticated and the notion of what kind of vulnerabilities actually matter is constantly changing. For example, timing attacks are now common threats, whereas only s few years ago they were considered exotic.