Eccouncil ICS-SCADA Exam Questions

Modbus TCP is a variant of the Modbus family of simple, networked protocols aimed at industrial automation applications. Unlike the original Modbus protocol, which runs over serial links, Modbus TCP runs over TCP/IP networks.

Port 502 is the standard TCP port used for Modbus TCP communications. This port is designated for Modbus messages encapsulated in a TCP/IP wrapper, facilitating communication between Modbus devices and management systems over an IP network.

Knowing the correct port number is crucial for network configuration, security settings, and troubleshooting communications within a Modbus-enabled ICS/SCADA environment.

Reference

Modbus Organization, 'MODBUS Application Protocol Specification V1.1b3'.

'Modbus TCP/IP -- A Comprehensive Network protocol,' by Schneider Electric.

The third generation of ICS/SCADA systems is considered distributed. This generation features systems that are networked and interconnected, typically using a variety of standard communication protocols. This distribution allows for broader connectivity and integration with other systems, enhancing operational flexibility and efficiency but also introducing more vectors for potential cyber threats. Reference:

Joseph Weiss, 'Protecting Industrial Control Systems from Electronic Threats'.

The third generation of ICS/SCADA systems is considered distributed. These systems emerged in the late 1990s and early 2000s and were designed to overcome the limitations of earlier generations by leveraging networked architectures.

Distributed Architecture: Third-generation systems distributed control functions across multiple interconnected devices and systems, providing greater scalability and flexibility.

Network Integration: These systems integrated more extensively with IT networks, allowing for remote monitoring and control.

Standard Protocols: Adoption of standard communication protocols (e.g., Ethernet, TCP/IP) facilitated interoperability and integration with other systems.

Enhanced Redundancy: Improved fault tolerance and redundancy were implemented to ensure system reliability.

Due to these features, the third generation is known as the distributed generation.

Reference

'SCADA Systems,' SCADAHacker, SCADA Generations.

TCP flags are used in the header of TCP segments to control the flow of data and to indicate the status of a connection. Valid TCP flags include:

FIN: Finish, used to terminate the connection.

PSH: Push, instructs the receiver to pass the data to the application immediately.

URG: Urgent, indicates that the data contained in the segment should be processed urgently.

RST: Reset, abruptly terminates the connection upon error or other conditions.

SYN: Synchronize, used during the initial handshake to establish a connection. These flags are integral to managing the state and flow of TCP connections. Reference:

Douglas E. Comer, 'Internetworking with TCP/IP Vol.1: Principles, Protocols, and Architecture'.

A Virtual Private Network (VPN) typically requires two Security Associations (SAs) for a secure communication session. One SA is used for inbound traffic, and the other for outbound traffic.

In the context of IPsec, which is often used to secure VPN connections, these two SAs facilitate the bidirectional secure exchange of packets in a VPN tunnel.

Each SA uniquely defines how traffic should be securely processed, including the encryption and authentication mechanisms. This ensures that data sent in one direction is handled independently from data sent in the opposite direction, maintaining the integrity and confidentiality of both communication streams.

Reference

'Understanding IPSec VPNs,' by Cisco Systems.

'IPsec Security Associations,' RFC 4301, Security Architecture for the Internet Protocol.

Port mirroring (also known as SPAN - Switched Port Analyzer) is considered one of the best ways to counter packet monitoring on a switch. This technique involves copying traffic from one or more switch ports (or an entire VLAN) to another port where the monitoring device is connected. Port mirroring allows administrators to monitor network traffic in a non-intrusive way, as it does not affect network performance and is transparent to users and endpoints on the network. Reference:

Cisco Systems, 'Catalyst Switched Port Analyzer (SPAN) Configuration Example'.