The paper is related to system and method for protection of an automated control system (ACS) against un-authorized devices connected to the ACS via wired or wireless channels that substantially obviates the disadvantages of the related art. The protection system monitors the signals spreading in the network analyzing the performance of the network for malicious code or hidden connections of attacker. The system is developed specifically for this purpose and it can protect the industrial control systems more effectively than standard anti-virus programs. Specific anti-virus software installed on a central server of the automated control system protects it from software-based attacks both from internal and external offenders. The system comprises a plurality of bus protection devices of different types, including any of a twisted-pair protection device, a power lines protection device, On-Board Diagnostics signal protocol protection device, and a wireless protection device.