Security of Safety Important I&C Systems - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 253

IMECA Technique

current transient, power consumption or path delay.
At the present time, main difficulties for applica-
tion of this approach are large process variation
(due to modern chip nanometer technologies) and
noises during parameters' measurement (that can
lead to masking of disturbances, generated by
HTs). Hence, such approaches to HT detection
can be based on the following principles:

The FMEA is a standard formalized technique
used in systems reliability analysis devoted to
the specification of failure modes, their sources,
causes and influence on system operability. “Fail-
ure modes” means the ways, or modes, in which
something might fail. Failures are any errors or
defects, especially ones that affect the customer,
and can be potential (that can happen) or actual
(that already happened). “Effects analysis” refers
to studying the consequences of those failures.
In FMEA-technique, all possible failures are
prioritized according to how serious their conse-
quences are, how frequently they occur and how
easily they can be detected.
FMEA is used during the design stage with an
aim to avoid failures in future. In the next stages
it is used for process control, before and during
ongoing operation of the process. The purpose
of the FMEA is to take actions to eliminate or
reduce possible failures, starting with the highest-
priority ones. It also may be used to evaluate
risk management priorities for mitigating known
threat-vulnerabilities.
IMECA (Intrusion Modes and Effects Criti-
cality Analysis) is a modification of FMEA that
takes into account possible intrusions to the system
(Babeshko, E. et al., 2008). Since any vulnerability
can become a failure if an intrusion occurs, we can
use IMECA to take into account failures caused
by intrusions “using” system vulnerabilities.
It should be noted that FMEA and IMECA are
not the only methods for complex systems failures
and risks analysis. Authors in several related papers
(e.g. Babeshko, E. et al., 2008) proved that IMECA
techniques is one of the most convenient and clear
in analysis of industrial Supervisory Control and
Data Acquisition (SCADA) systems consist-
ing of several hardware and specific software
components with different architectures. It was
performed an analysis of failures and intrusions
effects for software, hardware, stored data, users
and a SCADA-based system as a whole. Obtained

• Detection of speciic features of chip struc-
ture, using a signature (“inger-printing”)
obtained via measurement of one or more
parameters of side-channels.
• Measurement of power-supply transient
signal via calibration process (and further
subjected to statistical characterization) for
a signal, obtained from power ports of sev-
eral chips.
• Generation of test vectors to maximize the
activity in individual partitions of a chip,
with simultaneous minimizing the activity
of other segments.
• Cyclic replication of input test vectors to
increase total diference in power proile
between chip, which contains HTs, and
HTs-free chip.
• Use of path delays for output ports (possi-
bly together with value of leakage current)
with extensive characterization of process
variations.

ASSESSMENT OF I&C SYSTEMS
CYBER SECURITY

The objective of this subsection is to customize
the elements of gap analysis (GA), Intrusion
Modes and Effects Criticality Analysis (IMECA)
technique and analysis of development processes
related to the developer (human), technique, and
tool (HTT) to develop an approach, which can be
used in analysis and assessment of safety important
I&C systems cyber security.