A formal semantics of PLC programs in Coq

International audienceProgrammable logic Controllers (PLC) are embedded systems that are widely used in industry. We propose a formal semantics of the Instruction List (IL) language, one of the five programing languages defined in the IEC 61131-3 standard for PLC programing. This semantics support a significant subset of the IL language that includes on-delay timers. We formalized this semantics in the proof assistant Coq and used it to prove some safety properties on an example of PLC program.Programmable logic Controllers (PLC) sont des systèmes embarqués qui sont largement utilisés dans l'industrie. Nous proposons dans ce papier une sémantique formelle du langage Instruction List (IL), l'un des cinq langages de programmation défini dans la norme IEC 61131-3 pour la programmation des PLC. Cette sémantique prend en charge un sous-ensemble important du langage IL qui comprend les timers on-delay. Nous avons formalisé cette sémantique dans le système Coq et nous l'avons utilisé pour prouver certaines propriétés de sûreté sur un exemple de programme PLC

Programming a PLC controller with a Ladder Diagram

In this paper one industrial process and the automation of that industrial process are considered. In automation, the most important part is the controller. The controller is actually the brain of the process, and it regulates the switching on and off of all the elements involved in the process itself. The controllers that are used in industrial automation are called programmable logic controllers (PLC controllers). With an example it is shown how the PLC controller can be programmed with a Ladder Diagram. PLC programming involves creating a set of instructions that govern the behavior of a PLC to control machinery and processes. These instructions are written using specialized software tools and are executed in a sequential manner. The primary objectives of PLC programming are to ensure the safe and efficient operation of automated systems, maintain process accuracy, and facilitate quick responses to changing conditions

Preventing Capability Abuse through Systematic Analysis of Exposed Interface

Connectivity and interoperability are becoming more and more critical in today’s software and cyber-physical systems. Different components of the system can better collaborate, enabling new innovation opportunities. However, to support connectivity and interoperability, systems and applications have to expose certain capabilities, which inevitably expands their attack surfaces and increases the risk of being abused. Due to the complexity of software systems and the heterogeneity of cyber-physical systems, it is challenging to secure their exposed interfaces and completely prevent abuses. To address the problems in a proactive manner, in this dissertation, we demonstrate that systematic studies of exposed interfaces and their usage in the real world, leveraging techniques such as program analysis, can reveal design-level, implementation-level, as well as configuration-level security issues, which can help with the development of defense solutions that effectively prevent capability abuse. This dissertation solves four problems in this space. First, we detect inconsistent security policy enforcement, a common implementation flaw. Focusing on the Android framework, we design and build a tool that compares permissions enforced on different code paths and identifies the paths enforcing weaker permissions. Second, we propose the Application Lifecycle Graph (ALG), a novel modeling approach to describing system-wide app lifecycle, to assist the detection of diehard behaviors that abuse lifecycle interfaces. We develop a lightweight runtime framework that utilizes ALG to realize fine-grained app lifecycle control. Third, we study real-world programmable logic controller programs for identifying insecure configurations that can be abused by adversaries to cause safety violations. Lastly, we conduct the first systematic security study on the usage of Unix domain sockets on Android, which reveals both implementation flaws and configuration weaknesses.PHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/149960/1/yurushao_1.pd