Improving security in SCADA systems through firewall policy analysis

Modern SCADA networks are connected to both the companys enterprise network and the Internet. Because these industrial systems often control critical processes the cyber-security requirements become a priority for their design. This paper deals with the network security in SCADA environment implemented by firewall devices. We proposed a method for verification of firewall configurations against a security policy to detect and reveal potential holes in implemented rule sets. We present a straightforward verification method based on representation of a firewall configuration as a set of logical formulas suitable for automated analysis using SAT/SMT tools. We demonstrate how such configuration can be analyzed for security policy violation that can be inferred from a security policy specification of an industrial automation system.