Abstract
The current train systems are heavily computerized which makes them highly prone to cyberattacks. Many functions in the trains are controlled by programmable logic controllers (PLCs) which make them an attractive target of attacks. By compromising the train's PLCs, attackers can cause trains to operate in an unsafe environment and even lead to a fatal accident. In this paper, we investigated the current PLC redundancy framework in train systems which only resolves the issue of availability of the PLC while overlooking the integrity of the data being synchronized between PLCs. We proposed a new PLC redundancy framework encompassing of isolation and recovery mechanisms which are able to provide both availability and integrity. We developed a proof of concept and demonstrated its viability on our laboratory training skid.