In industrial control systems, devices such as Programmable Logic Controllers (PLCs) are commonly used to directly interact with sensors and actuators, and perform local automatic control. PLCs run software on two different layers: a) firmware (i.e. the OS) and b) control logic (processing sensor readings to determine control actions). In this work, we discuss ladder logic bombs, i.e. malware written in ladder logic (or one of the other IEC 61131-3-compatible languages). Such malware would be inserted by an attacker into existing control logic on a PLC, and either persistently change the behavior, or wait for specific trigger signals to activate malicious behaviour. For example, the LLB could replace legitimate sensor readings with manipulated values. We see the concept of LLBs as a generalization of attacks such as the Stuxnet attack. We introduce LLBs on an abstract level, and then demonstrate several designs based on real PLC devices in our lab. In particular, we also focus on stealthy LLBs, i.e. LLBs that are hard to detect by human operators manually validating the program running in PLCs. In addition to introducing vulnerabilities on the logic layer, we also discuss countermeasures and we propose two detection techniques.
In @cite_15 , Karnouskos discuss Stuxnet and how it managed to deviate the expected behaviour of PLC. @cite_8 , Kim discuss the cyber security issues in nuclear power plants and focused on stuxnet inherited malware attacks on control system, and its impacts in future along with its countermeasures.
@cite_15 @cite_8
2039148409 1982645273
Industrial systems consider only partially security, mostly relying on the basis of “isolated” networks, and controlled access environments. Monitoring and control systems such as SCADA DCS are responsible for managing critical infrastructures operate in these environments, where a false sense of security assumptions is usually made. The Stuxnet worm attack demonstrated widely in mid 2010 that many of the security assumptions made about the operating environment, technological capabilities and potential threat risk analysis are far away from the reality and challenges modern industrial systems face. We investigate in this work the highly sophisticated aspects of Stuxnet, the impact that it may have on existing security considerations and pose some thoughts on the next generation SCADA DCS systems from a security perspective. Abstract With the introduction of new technology based on the increasing digitalization of control systems, the potential of cyber attacks has escalated into a serious threat for nuclear facilities, resulting in the advent of the Stuxnet. In this regard, the nuclear industry needs to consider several cyber security issues imposed on nuclear power plants, including regulatory guidelines and standards for cyber security, the possibility of Stuxnet-inherited malware attacks in the future, and countermeasures for protecting nuclear power plants against possible cyber attacks.