atw Vol. 63 (2018) | Issue 5 ı May
ENVIRONMENT AND SAFETY 288
| | Fig. 6.
Attack Tree Analysis based on Security Controls.
then associated to a timeline. Therefore log file either
should be on or enabled.
Record 1
(deleted)
Record 2
(new generated)
4. Direct logging without relying on process
control software
Direct and completely independent logging of the data
is another detective security control. The data should
be stored in analog and binary variables before collecting
it together like in Security Information and Event
Management (SIEM) [20]. As shown in the Figure 7, the
values of regular changes in centrifuge pump speed could
be stored in a separate system before sending them to the
central data storage system. This security control will help
to keep the data secured in case of attacker makes any
changes in the central display of the data.
5. Other security controls
Periodical scan of the software should be done to avoid
some abnormal things in the system. And also handling of
new generated file is important to avoid any cyber-attack.
| | Fig. 7.
Direct Logging of Speed of a Centrifuge Pump.
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| | Tab. 1.
An Example of Naming Convention.
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NEI 08-09 requires log records are reviewed at least every
92 days, or as required by the Physical Security Plan.
In addition, each generated new file should follow the
predefined naming. Individual generated file should have
a source. In addition, new created file should have property
to specify its source as shown in the Table 1 so that no one
can override the existing file with malicious codes.
Conclusion
Non-targeted cybersecurity attacks, e.g. malware that is
not conceived for the manipulation a specific target,
can be sophisticated. Completely preventing these attacks
as well as Advance Persistent Threats cannot be addressed
only by protective security controls. Detective security
controls are necessary to identify attacks within a
reasonable time frame and they are the precondition
for initiating the application of protective controls.
Accordingly, resilient implementations of detective
security controls are needed, in line with the stringency
of the security grading. In this paper the most important
detective controls, like the logging at all relevant levels
were addressed. The benefits of securing the information
generated by the detective controls by using data diodes
were explained together with example architectures
that merge the collected security intelligence as input
of a central Security Information and Event System.
As two important conceptual extensions, the security
controls based on independent data collection, directly
from physical devices and the monitoring and evaluation
of analog and binary signal value transients were
introduced. Implementing appro priate combinations of
these resilient detective security controls will help in
improving the security posture of refurbished and new
power plants.
Environment and Safety
Detective Application Security Controls for Nuclear Safety ı Deeksha Gupta, Karl Waedt and Yuan Gao
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