Unauthorized interference

Unauthorized interference with computer hardware is usually difficult, but interference with peripheral equipment may be more serious than on a traditional plant, as the computer will not know that interference has occurred. For example, the leads on a limit switch on a valve were interchanged to carry out some tests. The plant was on manual control at the time but was switched back to computer control before the leads were restored to their coirect positions. The computer thought the valve was open (when it was shut) and elected to close it. It actually opened it, releasing flammable material [2]. 

If the plant had been controlled conventionally, the operators involved may have known of the temporary interchange of the leads, or a notice could have been placed on the panel informing them. However, it would be difficult to tell the computer that the valve is open when the signal says it is shut A computer provides new opportunities for familiar communication errors. 

Files had to be transferred from a control computer to a training simulator. At first, there was no direct connection the files were first transferred to a freestanding workstation and then from there to the simulator. To simplify the transfer, a direct cable connection was made between the control computer and the simulator. 

Unfortunately the address of the gateway in the control computer used for the data transfer was the same as that used to connect to the distributed control system (dcs). As a result data flowed from the simulator through the control computer to the dcs and replaced the current input data by historic data. Some conditions on the plant started to change, but fortunately this was soon noticed by alert operators, and the plant was brought back under control. 

Connecting a control computer to another system is a modification and should only be carried out after systematic study of possible consequences (see Section 20.4.3). If made, data flow should be possible only in the outward direction (see text through the end of this section). All systems should be secure. Houses need doors. The doors on control systems are less tangible than those on houses but just as important. 

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According to the definition used in the Russian regulations, the physical protection system (PPS) of a nuclear power plant is a system of measures to exclude unauthorized interference in the operation of systems for the control and assurance of safe operation of the reactor and to prevent access to the nuclear materials. 

A small hleed-off pipe is taken from the pump discharge, with an adjusting valve, and led to waste. This can he more easily adjusted and works only when the condenser is running, hut is subject to interference by unauthorized persons. 

Unauthorized or unexpected entry of employees, contractors, employees of service organizations (such as postal and utilities), or other visitors, and the activities of these persons, could cause process upsets, could aggravate the consequences of hazardous incidents, and could interfere with emergency or rescue activities. A procedure should be established to control the entry and document the exit of persons from areas in which hazardous materials are handled. 

Preventing unauthorized access into a warehouse may require certain security features. Unauthorized access may be motivated by theft or other illegal or destructive purposes. There may also be a need to restrict employee access into an area of a warehouse storing toxic or potentially hazardous materials. The type and extent of security features utilized should be based upon the risk associated with unauthorized entry. Security features, such as door locks, alarm systems, closed circuit television (CCTV) monitors, should not interfere with required means of egress. 

New communication services must share bands with existing NB transmitters Multipath in indoor and urban communication environments Need to generate signals that will not interfere with existing communication links Need to generate signals that are unUkely to cause EMI Prevent unauthorized demodulation New multiple access format... 

According to M. Barzilay of ISACA Cyber security is the sum of efforts invested in addressing cyber risk... From an ISA point of view, security issue refers to the prevention of illegal or unwanted penetration, intentional or unintentional interference with the proper and intended operation, or inappropriate access to confidential information in industrial automation and control systems [17]. Cyber security therefore is mainly concerned with protection against unauthorized access (intentional or unintentional) to save data and information systems from theft or damage to prevent the system from any disruption of operation and unwanted functioning of the system. lEC/lSA 62443 (formerly ISA 99) is the relevant standard. Many propose to treat cyber risks as physical risks, that is, to check and assess vulnerability, frequency of occurrence, consequences, etc. 

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