Cyber-Physical Systems Security—A Survey <s> B. ICS Challenges 1) Change Management: <s> The purpose of this document is to provide guidance for securing industrial control systems (ICS), including supervisory control and data acquisition (SCADA) systems, distributed control systems (DCS), and other systems performing control functions. The document provides an overview of ICS and typical system topologies, identifies typical threats and vulnerabilities to these systems, and provides recommended security countermeasures to mitigate the associated risks. Because there are many different types of ICS with varying levels of potential risk and impact, the document provides a list of many different methods and techniques for securing ICS. The document should not be used purely as a checklist to secure a specific system. Readers are encouraged to perform a risk-based assessment on their systems and to tailor the recommended guidelines and solutions to meet their specific security, business and operational requirements. The scope of this document includes ICS that are typically used in the electric, water and wastewater, oil and natural gas, chemical, pharmaceutical, pulp and paper, food and beverage, and discrete manufacturing (automotive, aerospace, and durable goods) industries. <s> BIB001 </s> Cyber-Physical Systems Security—A Survey <s> B. ICS Challenges 1) Change Management: <s> Increasing awareness of ICS security issues has brought about a growing body of work in this area, including pioneering contributions based on realistic control system logs and network traces. This paper surveys the state of the art in ICS security research, including efforts of industrial researchers, highlighting the most interesting works. Research efforts are grouped into divergent areas, where we add “secure control” as a new category to capture security goals specific to control systems that differ from security goals in traditional IT systems. <s> BIB002
The ICS environment spans diverse geographical locations that involve various systems that need to be replaced, updated, or removed at some point. For example, in ICS, a system update needs careful planning to avoid unexpected failure as it has occurred in a nuclear plant due to an update in a computer in the business network of the plant  . In addition, there are many stakeholders who can affect the security posture unintentionally. Therefore, a coordinated change management should be introduced to prevent and detect security-related changes in the ICS application  , BIB001 . 2) Malicious Insider: This is probably one of the most difficult challenges to defend against. Insiders could cause security problems either intentionally or unintentionally. For example, an insider could leverage the trust given to her/him along with acquired inside knowledge to launch an attack, such as the Maroochy water and sewage system, or help remote attackers, such as Stuxnet propagation via an USB stick. Unintentional cases where insiders unknowingly use an infected laptop or USB stick that could give remote attackers access points to the ICS. The malicious insider challenge has been underestimated and overlooked, and it certainly needs serious considerations BIB002 . 3) Secure Integration: As ICS relies heavily on legacy systems, it is inherently vulnerable to their vulnerabilities. Therefore, the integration of new components with legacy systems must be done securely so that it does not result in new security vulnerabilities. In addition, due to the large number of legacy components in ICS, it is economically infeasible to replace all of them with more secure ones BIB002 . Meanwhile, their security should not be ignored and short-term TABLE VI CYBER-PHYSICAL SECURITY FRAMEWORK. C: CYBER, CP: CYBER-PHYSICAL, AND P: PHYSICAL solutions must be implemented to minimize any potential risks  .