On Ladder Logic Bombs in Industrial Control Systems

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.Comment: 11 pages, 14 figures, 2 tables, 1 algorith

Defending Against Firmware Cyber Attacks on Safety-Critical Systems

In the past, it was not possible to update the underlying software in many industrial control devices. Engineering teams had to ‘rip and replace’ obsolete components. However, the ability to make firmware updates has provided significant benefits to the companies who use Programmable Logic Controllers (PLCs), switches, gateways and bridges as well as an array of smart sensor/actuators. These updates include security patches when vulnerabilities are identified in existing devices; they can be distributed by physical media but are increasingly downloaded over Internet connections. These mechanisms pose a growing threat to the cyber security of safety-critical applications, which are illustrated by recent attacks on safety-related infrastructures across the Ukraine. Subsequent sections explain how malware can be distributed within firmware updates. Even when attackers cannot reverse engineer the code necessary to disguise their attack, they can undermine a device by forcing it into a constant upload cycle where the firmware installation never terminates. In this paper, we present means of mitigating the risks of firmware attack on safety-critical systems as part of wider initiatives to secure national critical infrastructures. Technical solutions, including firmware hashing, must be augmented by organizational measures to secure the supply chain within individual plants, across companies and throughout safety-related industries

Forensic Attacks Analysis and the Cyber Security of Safety-Critical Industrial Control Systems

Industrial Control Systems (ICS) and SCADA (Supervisory Control And Data Acquisition) applications monitor and control a wide range of safety-related functions. These include energy generation where failures could have significant, irreversible consequences. They also include the control systems that are used in the manufacture of safety-related products. In this case bugs in an ICS/SCADA system could introduce flaws in the production of components that remain undetected before being incorporated into safety-related applications. Industrial Control Systems, typically, use devices and networks that are very different from conventional IP-based infrastructures. These differences prevent the re-use of existing cyber-security products in ICS/SCADA environments; the architectures, file formats and process structures are very different. This paper supports the forensic analysis of industrial control systems in safety-related applications. In particular, we describe how forensic attack analysis is used to identify weaknesses in devices so that we can both protect components but also determine the information that must be analyzed during the aftermath of a cyber-incident. Simulated attacks detect vulnerabilities; a risk-based approach can then be used to assess the likelihood and impact of any breach. These risk assessments are then used to justify both immediate and longer-term countermeasures

MiniCPS: A toolkit for security research on CPS Networks

In recent years, tremendous effort has been spent to modernizing communication infrastructure in Cyber-Physical Systems (CPS) such as Industrial Control Systems (ICS) and related Supervisory Control and Data Acquisition (SCADA) systems. While a great amount of research has been conducted on network security of office and home networks, recently the security of CPS and related systems has gained a lot of attention. Unfortunately, real-world CPS are often not open to security researchers, and as a result very few reference systems and topologies are available. In this work, we present MiniCPS, a CPS simulation toolbox intended to alleviate this problem. The goal of MiniCPS is to create an extensible, reproducible research environment targeted to communications and physical-layer interactions in CPS. MiniCPS builds on Mininet to provide lightweight real-time network emulation, and extends Mininet with tools to simulate typical CPS components such as programmable logic controllers, which use industrial protocols (Ethernet/IP, Modbus/TCP). In addition, MiniCPS defines a simple API to enable physical-layer interaction simulation. In this work, we demonstrate applications of MiniCPS in two example scenarios, and show how MiniCPS can be used to develop attacks and defenses that are directly applicable to real systems.Comment: 8 pages, 6 figures, 1 code listin

Securing the Participation of Safety-Critical SCADA Systems in the Industrial Internet of Things

In the past, industrial control systems were ‘air gapped’ and isolated from more conventional networks. They used specialist protocols, such as Modbus, that are very different from TCP/IP. Individual devices used proprietary operating systems rather than the more familiar Linux or Windows. However, things are changing. There is a move for greater connectivity – for instance so that higher-level enterprise management systems can exchange information that helps optimise production processes. At the same time, industrial systems have been influenced by concepts from the Internet of Things; where the information derived from sensors and actuators in domestic and industrial components can be addressed through network interfaces. This paper identifies a range of cyber security and safety concerns that arise from these developments. The closing sections introduce potential solutions and identify areas for future research