  Control systems behavior can be analyzed taking into account a large number
of parameters: performances, reliability, availability, security. Each control
system presents various security vulnerabilities that affect in lower or higher
measure its functioning. In this paper the authors present a method to assess
the impact of security issues on the systems availability. A fuzzy model for
estimating the availability of the system based on the security level and
achieved availability coefficient (depending on MTBF and MTR) is developed and
described. The results of the fuzzy inference system (FIS) are presented in the
last section of the paper.
