Skip to content

Page116

Industrial Control Systems (ICS)

Industrial Control Systems (ICS) are computers used by industries such as power generation, manufacturing, and automation. Historically the protocols used in Industrial Control Systems, such as Modbus, were plaintext and quite insecure. This risk was mitigated by the fact that these systems were (previously) commonly segmented from the Internet and relied on serial communications (much like modems) to communicate within one facility. That has changed considerably over the years, and these systems are now commonly connected to the Internet. Protocols such as Modbus, which previously used serial lines, have been updated to use TCP/IP (Modbus TCP). Unfortunately, Modbus TCP is plaintext, requiring encrypted tunnels to be transmitted securely.

Dong-Ho Kang, Byoung-Koo Kim, Jung-Chan Na describe Modbus: There are no security elements in the Modbus. Any attacker that can reach a Modbus server will be able to read and write to the field device as well as reboot the device and run diagnostic commands. The simplicity of the Modbus protocol and widespread availability of free Modbus clients makes it relatively simple to attack a Modbus server [25].

Important ICS terms to know include the following:

  • Supervisory Control and Data Acquisition (SCADA): A SCADA (or supervisory control and data acquisition) system means a system consisting of a number of remote terminal units (or RTUs) collecting field data connected back to a master station via a communications system.
  • Remote Terminal Unit (RTU): An RTU (sometimes referred to as a Remote Telemetry Unit) as the title implies, is a standalone data acquisition and control unit, generally microprocessor based, which monitors and controls equipment at some remote location from the central station.
  • Distributed Control Systems (DCS): In a DCS, the data acquisition and control functions are performed by a number of distributed microprocessor-based units situated near to the devices being controlled or the instrument from which data is being gathered [26].
  • Programmable Logic Controllers (PLC): a small, modular solid state computer with customized instructions for performing a particular task. PLCs, which are used in industrial control systems (ICS) for a wide variety of industries, have largely replaced mechanical relays, drum sequencers and cam timers [27].