Cloud-Assisted IoT-Based SCADA Systems Security: A Review of the State of the Art and Future Challenges <s> A. SCADA SYSTEMS SECURITY IN GENERAL <s> New technologies are increasing the vulnerability of the power system to cyber security threats. Dealing with these threats and determining vulnerabilities is an important task for utilities. This paper presents the development of a testbed designed to assess the vulnerabilities introduced by using public networks for communication. <s> BIB001 </s> Cloud-Assisted IoT-Based SCADA Systems Security: A Review of the State of the Art and Future Challenges <s> A. SCADA SYSTEMS SECURITY IN GENERAL <s> Supervisory control and data acquisition (SCADA) networks have replaced discrete wiring for many industrial processes, and the efficiency of the network alternative suggests a trend toward more SCADA networks in the future. This paper broadly considers SCADA to include distributed control systems (DCS) and digital control systems. These networks offer many advantages, but they also introduce potential vulnerabilities that can be exploited by adversaries. Inter-connectivity exposes SCADA networks to many of the same threats that face the public internet and many of the established defenses therefore show promise if adapted to the SCADA differences. This paper provides an overview of security issues in SCADA networks and ongoing efforts to improve the security of these networks. Initially, a few samples from the range of threats to SCADA network security are offered. Next, attention is focused on security assessment of SCADA communication protocols. Three challenges must be addressed to strengthen SCADA networks. Access control mechanisms need to be introduced or strengthened, improvements are needed inside of the network to enhance security and network monitoring, and SCADA security management improvements and policies are needed. This paper discusses each of these challenges. This paper uses the Profibus protocol as an example to illustrate somemore » of the vulnerabilities that arise within SCADA networks. The example Profibus security assessment establishes a network model and an attacker model before proceeding to a list of example attacks. (authors)« less <s> BIB002 </s> Cloud-Assisted IoT-Based SCADA Systems Security: A Review of the State of the Art and Future Challenges <s> A. SCADA SYSTEMS SECURITY IN GENERAL <s> Purpose – Supervisory control and data acquisition (SCADA) systems are widely used by utility companies during the production and distribution of oil, gas, chemicals, electric power, and water to control and monitor these operations. A cyber attack on a SCADA system cannot only result in a major financial disaster but also in devastating damage to public safety and health. The purpose of this paper is to survey the literature on the cyber security of SCADA systems and then suggest two categories of security solutions.Design/methodology/approach – The paper proposes the use of secure socket layer/transport layer security (SSL/TLS) and IP security (IPsec) solutions, implemented on the test‐bed at the University of Louisville, as the optimal choices when considering the level of security a solution can provide and the difficulty of implementing such a security measure. The paper analyzes these two solution choices, discuss their advantages and disadvantages, and present details on efficient ways of implement... <s> BIB003 </s> Cloud-Assisted IoT-Based SCADA Systems Security: A Review of the State of the Art and Future Challenges <s> A. SCADA SYSTEMS SECURITY IN GENERAL <s> Cyber security threats and attacks are greatly affecting the security of critical infrastructure, industrial control systems, and Supervisory Control and Data Acquisition (SCADA) control systems. Despite growing awareness of security issues especially in SCADA networks, there exist little or scarce information about SCADA vulnerabilities and attacks. The emergence of Internet and World Wide Web technologies integrated with business systems brought a growing concern about the security and safety of the SCADA control systems. This research aims to addresses the issues regarding security and vulnerability testing. Software program was created to simulate the vulnerability testing and carry out assessment methodologies to test existing SCADA software design and implementation. This paper provides an analysis of potential software vulnerabilities, and security concerns including recommendations toward improving security for SCADA control systems. It also provides recommendations on key requirements and features needed for the enhancement of security for SCADA control systems. <s> BIB004 </s> Cloud-Assisted IoT-Based SCADA Systems Security: A Review of the State of the Art and Future Challenges <s> A. SCADA SYSTEMS SECURITY IN GENERAL <s> In the last years there has been an increasing interest in the security of process control and SCADA systems. Furthermore, recent computer attacks such as the Stuxnet worm, have shown there are parties with the motivation and resources to effectively attack control systems. While previous work has proposed new security mechanisms for control systems, few of them have explored new and fundamentally different research problems for securing control systems when compared to securing traditional information technology (IT) systems. In particular, the sophistication of new malware attacking control systems--malware including zero-days attacks, rootkits created for control systems, and software signed by trusted certificate authorities--has shown that it is very difficult to prevent and detect these attacks based solely on IT system information. In this paper we show how, by incorporating knowledge of the physical system under control, we are able to detect computer attacks that change the behavior of the targeted control system. By using knowledge of the physical system we are able to focus on the final objective of the attack, and not on the particular mechanisms of how vulnerabilities are exploited, and how the attack is hidden. We analyze the security and safety of our mechanisms by exploring the effects of stealthy attacks, and by ensuring that automatic attack-response mechanisms will not drive the system to an unsafe state. A secondary goal of this paper is to initiate the discussion between control and security practitioners--two areas that have had little interaction in the past. We believe that control engineers can leverage security engineering to design--based on a combination of their best practices--control algorithms that go beyond safety and fault tolerance, and include considerations to survive targeted attacks. <s> BIB005 </s> Cloud-Assisted IoT-Based SCADA Systems Security: A Review of the State of the Art and Future Challenges <s> A. SCADA SYSTEMS SECURITY IN GENERAL <s> Distributed control systems (DCS) and supervisory control and data acquisition (SCADA) systems were developed to reduce labour costs, and to allow system-wide monitoring and remote control from a central location. Control systems are widely used in critical infrastructures such as electric grid, natural gas, water and wastewater industries. While control systems can be vulnerable to a variety of types of cyber attacks that could have devastating consequences, little research has been done to secure the control systems. American Gas Association (AGA), IEC TC57 WG15, IEEE, NIST and National SCADA Test Bed Program have been actively designing cryptographic standard to protect SCADA systems. American Gas Association (AGA) had originally been designing cryptographic standard to protect SCADA communication links and finished the report AGA 12 part 1. The AGA 12 part 2 has been transferred to IEEE P1711. This paper presents an attack on the protocols in the first draft of AGA standard (Wright et al., 2004). This attack shows that the security mechanisms in the first version of the AGA standard protocol could be easily defeated. We then propose a suite of security protocols optimised for SCADA/DCS systems which include: point-to-point secure channels, authenticated broadcast channels, authenticated emergency channels, and revised authenticated emergency channels. These protocols are designed to address the specific challenges that SCADA systems have. <s> BIB006 </s> Cloud-Assisted IoT-Based SCADA Systems Security: A Review of the State of the Art and Future Challenges <s> A. SCADA SYSTEMS SECURITY IN GENERAL <s> An overview of supervisory control and data acquisition (SCADA) systems is presented and relevant security concerns are addressed. To secure IP-based SCADA systems, it is vital to implement secure architectures which prevent access to the SCADA from corporate IT, in addition to excellent management practices in managing IP-based networks. We give an overall explanation of SCADA systems along with their security concerns and vulnerability. In the case of legacy SCADA systems, the concerns regarding security were minimal since it used proprietary networks; however, since the move of SCADA systems to the Internet, security problems have become an imperative issue, especially problems regarding IP-based systems. We also discuss various forms of threats and vulnerabilities on future SCADA systems applied with IPv6 over low-power, wireless personal area networks (6LoWPANs) and suggest security management methods to overcome these concerns. In order to identify and remove various vulnerabilities and threats to SCADA systems over IP-based wireless sensor networks, especially for 6LoWPAN applications, we examine possible threats and propose proper and precise security management methods. <s> BIB007 </s> Cloud-Assisted IoT-Based SCADA Systems Security: A Review of the State of the Art and Future Challenges <s> A. SCADA SYSTEMS SECURITY IN GENERAL <s> Cyber-Physical Systems (CPSs) are systems in which software and hardware entities monitor and manage physical devices using communication channels. They have become ubiquitous in many domains including health monitoring, smart vehicles and energy efficiency as in smart buildings and smart grid operations. The introduction of a digital control system and a communication channel, to exchange data with the physical system, increases the chance of vulnerabilities in the overall system. This paper presents the state-of-the-art of the security vulnerabilities of such systems as well as the possible methods to mitigate/reduce such threats. We will describe recent promising solutions to guarantee confidentiality and authentication of the transported data in building automation network domains, and present ideas to analyze and formally verify the control commands issued by the (possibly compromised) control network computers for execution on SCADA system actuators. The purpose of the latter approach is to prevent malicious parties from injecting malicious commands and potentially driving the underlying physical system into an unsafe state. <s> BIB008 </s> Cloud-Assisted IoT-Based SCADA Systems Security: A Review of the State of the Art and Future Challenges <s> A. SCADA SYSTEMS SECURITY IN GENERAL <s> Industrial Control Systems (ICS) which among others are comprised of Supervisory Control and Data Acquisition (SCADA) and Distributed Control Systems (DCS) are used to control industrial processes. ICS have now been connected to other Information Technology (IT) systems and have as a result become vulnerable to Advanced Persistent Threats (APT). APTs are targeted attacks that use zero-day attacks to attack systems. Current ICS security mechanisms fail to deter APTs from infiltrating ICS. An analysis of possible solutions to deter APTs was done. This paper proposes the use of Artificial Immune Systems to secure ICS from APTs. <s> BIB009
The following general security considerations apply to SCADA systems: 1) Policy Management: Cyber security is considered a threat because if an intruder somehow gains access to a SCADA system then the intruder most probably also gains control over everything within the system. The threats increase enormously when these systems are connected to the Internet. For example, protecting SCADA systems against Internet connectivity was not even considered a possible vulnerability when power systems were first developed. Because people often have little awareness of the methods for securing CIs, cyberattacks are increasing. To assess power system vulnerabilities, an attack tree model was used by Watts  . The author argues that good password policies make the system access points strong and make it difficult for an intruder to guess a password to access the systems. A drawback of this methodology is that attack trees do not capture the penetration sequence of attack leaves. Cagalaban et al. BIB004 present a fault detection algorithm to find the vulnerabilities in SCADA system software. The authors of BIB004 used a test-bed architecture and the Modbus protocol. The purpose of an attacker can be easily identified by this methodology. The results reveal that SCADA systems software strength increases when these systems follow proper rules for authentication and authorization. 2) Data Integrity: To mitigate Denial of Service (DoS) attacks, Davis et al. BIB001 adopted a test-bed architecture using RINSE, which also assesses vulnerabilities faced by power systems. Three attack scenarios are considered. In the first scenario, there is no attack and systems perform normally; in the second scenario, the DoS attack is introduced; and the last scenario applies filters such that the effects of a DoS attack can be measured. A drawback of this methodology is that it focuses only on the software level; hence, hardware is not taken into consideration. Giani et al.  , presented a test-bed architecture in which system availability and integrity are compromised by introducing multiple attacks. The major goal of this study was to measure the impact that such attacks have on SCADA systems. Davis et al. BIB001 proposed a few models to investigate attacks, determine their effects, and identify mitigation strategies. Cárdenas et al. BIB005 presented a methodology that detects such attacks by monitoring and analyzing the physical system under observation. As recommended by BIB005 , attack-resilient algorithms are required to make the systems able to survive intentional attacks such as Stuxnet. 3) Weak Communication: According to Wang BIB006 , the communication links of SCADA systems can be attacked easily because they do not typically provide encryption and authentication mechanisms. The American Gas Association (AGA) has played a vital role in securing SCADA system communications and introduced the concept of cryptography within these systems' communication. Secure SCADA (sSCADA), a plugin device, is presented in BIB006 as Part 1 of the AGA's cryptographic standard, with two vulnerabilities that lead to man-in-the-middle and replay attacks. To address these vulnerabilities, the authors propose four channels of communication, each fulfilling different security services. The job of an attacker is made easy by the use of a weak protocol. The communication protocols used in SCADA systems are responsible for communicating messages over the entire industry network. Many protocols are used including DNP3, PROFIBUS, Ethernet/IP, etc., but based on the system requirements a particular protocol is selected for communication. The devices that were considered as trusted were connected to the SCADA systems network long before security issues were taken into consideration. Use of the new Internet-based technologies established untrusted connections. Hence, we can say that the builtin vulnerability of the communication protocols makes the systems weak. Igure and Williams BIB002 described three challenges that must be considered to improve SCADA system networks, as follows: -SCADA systems security within the network can be improved by utilizing intrusion detection systems and keeping firewalls up to date, thereby keeping the system's activities under constant supervision. -SCADA systems security management can be improved by performing regular risk assessments and improving the clarity of security plans and their implementations. -Access control for SCADA systems can be improved as well. The first step in securing any system is to prevent the system from being accessed by unauthorized entities. Although this can be achieved by improving authorization password and smart cards, those are not the ultimate solution. To assess and analyze the Modbus communication protocol's vulnerability and risks, Byres et al.  used an attack tree model, revealing that the Modbus protocol is weak and lacks basic security requirements such as integrity, confidentiality and authentication. They recommended  using firewalls, Intrusion Detection Systems (IDSs) and encryption techniques for secure communications. To secure the communication channels of SCADA systems, Patel and Sanyal BIB003 presented some solutions based on IP-Sec and SSL/TLS. The strengths and weakness of both presented solutions are also described in detail. On the network layer IP-Sec is presently capable of providing protection to each application responsible for carrying out communication tasks between two hosts. IP-Sec can secure the IP traffic, prevent DoS attacks, and is also able to stop any arbitrary communication packet from entering the TCP layer. Over TCP/IP, communications between (Remote Terminal Unit) RTUs and (Master Terminal Units) MTUs are secured by SSL/TLS, which is an efficient and fast solution and at the same time provides protection against man-in-themiddle and replay attacks. However, IP-Sec is also a complex and less scalable solution that is unable to provide nonrepudiation and authentication BIB003 . In addition, IP-Sec encrypts all the traffic. Similarly, SSL/TLS is considered to be an expensive solution with known vulnerabilities and is also unable to provide nonrepudiation. Although both IP-Sec and SSL have their drawbacks, the clients need determine which solution to use. Security in IP-based SCADA systems is addressed in detail in BIB007 . In another approach to securing the communication channels of SCADA systems, two middleware methods are described by Khelil et al.  . In the first method, the aim of the authors is to maintain data integrity and availability based on peer-to -peer protection by maintaining more than one copy of data. This data access technique can protect SCADA systems from router crashes as well as from data modifications. However, this approach is considered to be intrusive and requires modifications to be made on existing networks. In the second method, data availability is approached by using GridStat middleware. To ensure data availability, this methodology adds some new components to the architecture that require no changes to the original components: it follows a nonintrusive approach. Antonini et al. BIB008 addressed security challenges to SCADA systems, and Baker et al.  presented a security oriented cloud platform for Service Oriented Architecture (SOA) based SCADA systems. The main idea of this proposal is to deliver an innovative solution to integrate cloud platforms into SOA based SCADA systems. It also focuses on the enhancement of security and integrity concerns for these systems. Smart Grid systems are used in the proposed approach through a real-world scenario. This paper directs readers' attention toward building a secure cloud platform that supports the use of SOA based SCADA systems. Another threat stems from APTs, which are focused on networks. In this type of attack, an unauthorized person manages to enter a network and then tries to steal data from the system. The focus of this attack is not to cause damage but rather to stay undetected as long as possible, steal data and then leave, all the while keeping the attacker's identity hidden. Bere and Muyingi BIB009 addressed these types of threats and claim that APTs use zero-day vulnerabilities to steal data from systems.