Week 4 - Industrial Control System Flashcards
Industrial Control System
A control system that is designed for use in an industrial environment.
It perform several actions such as logic, sequencing, timing, counting and arithmetic to control multiple machines and/or processes.
These actions are performed by sensing the environment through their inputs and generating appropriate signals on their output.
Prioritized safety and reliability, however, the integration of digital technology in CPSs brings new challenges
Safety
Measures and protocols put in place to prevent accidents, disasters, or incidents that could harm people or the environment.
Reliability
Ensuring that critical infrastructure systems operate consistently and predictably without unexpected failures.
This often involves redundant systems, regular maintenance
Fault detection, Isolation & recovery
The process of identifying when something goes wrong in the system.
Involves determining the source of the problem and separating it from the rest of the system to prevent further damage.
Refers to the actions taken to restore the system to normal operation after a fault has been identified and isolated
Level 4 & 5: Enterprise zone
Business networks and enterprise systems.
Internet protocol (IP).
All IT security solutions can be applied here.
Level 3: Control zone
Real-time control elements in SCADA* systems.
Could be IP.
Devices in this zone may not be updated as often.
Few cybersecurity solutions can be applied here
Level 2,1,0: Field zone
Devices and networks in charge of control and automation.
It hosts the CPSs.
Devices in this zone have embedded devices, programmable logic control (PLC).
Variety of protocols including IP.
IT security solutions are rarely applicable.
AMI Headend
In the context of Advanced Metering Infrastructure (AMI), refers to a central system or server that serves as the nerve center of the AMI network.
The term “headend” is borrowed from the telecommunications industry, where it typically refers to a facility that receives and processes signals from multiple sources and then distributes them to the appropriate destinations.
Field Systems
Real-time (interact with its environment, continuously accepting requests from the environment and continuously producing reactions).
Strict requirements in terms of reliability and safety.
Implemented with severe resources constraints.
Often relying on legacy platforms that are not updated or patched, and using proprietary communication protocols.
Lack of antivirus software for embedded systems.
Monitoring and software protection is limited due to limited power and resources of embedded devices.
Purdue Model
A structural model for industrial control system (ICS) security, concerning physical processes, sensors, supervisory controls, operations, and logistics.
Defines the different levels of critical infrastructure used in production lines and how to secure them.
Similar to TCP/IP or OSI models but for ICS security and generally OT not IT.
There are different variations of the reference model, just like OSI and TCP/IP models.
Purdue Model Level 4 & 5 (Enterprise)
This is typically the IT network where primary business functions occur.
It provides business direction and orchestrates manufacturing operations.
Disruptions can lead to significant downtime and potential revenue loss.
Purdue Model - Level 4 & 5 (Enterprise) - ERP Systems
Systems that drive plant production schedules, material use, shipping, and inventory levels.
Examples include Oracle, SAP, Microsoft, and Epicor.
Purdue Model - Level 4 & 5 (Enterprise) - Core Business Services
Includes email, management, billing, customer services, and remote access to IT network.
These services are managed by IT personnel.
Purdue Model Level 3: Site-Wide Supervisory
Monitoring and operational support for a site or region.
Components:
Management servers,
Human-machine interfaces (HMIs), Alarm servers,
Analytic systems,
Historians (if scoped for an entire site or region);
Key Functions:
Oversee and manage site operations.
Purdue Model Level 2: Local Supervisory
Supervisory control for a single process, cell, line, or distributed control system (DCS).
Components:
HMIs,
Alarm servers,
Process analytic systems,
Historians,
Control room (if scoped for a single process, not site/region);
Key Functions:
Control and supervise individual processes.
Purdue Model Level 1: Local Controllers
Automated control of a process, cell, line, or DCS.
Components:
PLCs (Programmable Logic Controllers),
Control processors,
Programmable relays,
RTUs (Remote terminal units),
Process-specific microcontrollers;
Key Functions:
Automate specific processes.
Purdue Model Level 0: Field Devices
Sensors and actuators for a process, cell, line, or DCS.
Components:
Basic sensors and actuators,
Smart sensors/actuators using fieldbus protocols,
IEDs (Intelligent Electronic Devices),
IIoT devices (Industrial Internet-of-Things,
Communications gateways,
Other field instrumentation;
Key Functions:
Sense and actuate physical processes.
Key Aspects of the Purdue Model
The boundary point between Levels 0-3 (ICS/OT) and Levels 4-5 (IT) is crucial.
Historically, an “air gap” separated IT and OT, but as data demands increased, firewalls with DMZs were introduced.
Some believe it’s outdated due to technological advances, while others find it useful for conceptual security framework.
SANS ICS410 Reference Model
Expands upon the Purdue Model and offers explicit enforcement boundaries for ICS devices and cybersecurity controls.
It introduces segmentation for various ICS applications, including WAN communication and safety systems.
Common Concepts in ICS Cybersecurity Standards
Various frameworks and publications provide guidance for securing ICS, emphasizing segmentation and security controls at network boundaries.
Key concepts include asset management, security program development, secure architecture, incident response, access management, data protection, and security event monitoring.
Best Practices for Modern ICS Security Architectures
Effective network architecture is critical for ICS security.
Perimeter firewalls and enforcement boundaries control communication and provide choke points for monitoring.
Baseline “normal” communication to detect anomalies and threats.
Detailed network architecture guidelines, including secure remote access and dedicated infrastructure.
Cloud Integration and Evolving ICS Architectures
Devices requiring cloud access should be placed in separate zones restricting network access to the cloud controllers and on-premises systems they need to communicate with.
Secure Remote Access for ICS
Should pass through the demilitarized zone (DMZ) between IT and OT segments. DMZ services include hosting remote access connections, managing cloud connectivity, serving as IT gateways into OT, and OT gateways into IT environments.
Best Practices for Remote Access Connectivity
Remote connections through DMZs enhance visibility, tracking, logging, authentication, and access control.
Remote connectivity for OT staff involves a VPN connection into the ICS DMZ, followed by a second connection using hardened Remote Desktop (RD) via a jump host with role-based access into OT systems.
