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TABLE 6-29: RELATION OF EFFECTIVENESS AND LEVEL OF THREAT SCALES
Level of Threat scale
The evaluation scale for a level of threat evaluation using effectiveness is based on the
security measure characteristics that provide protection in the specific threat scenario.
The security measure characterization in section 3.5 provides the generic effectiveness
of security measures. The level of threat evaluation determines the specific
effectiveness of a security measure against one threat. While a security measure will
not be more effective than its generic effectiveness, its protection capabilities may be
limited against certain threats. And there can be threat scenarios where a security
measure provides no protection at all. For example if the specific threat targets another
security attribute (i.e. availability) than the security measure protects.
The level of threat evaluation also considers the dependencies and influences between
security measures by evaluating the combined effectiveness of security measures in a
The effectiveness evaluation is not limited to technical security measures but can be
used for any security measure, including operational security measures.
Effectiveness of protection scale
To make the effectiveness of protection calculation mathematically stable and avoiding
inaccuracies resulting from rounding, the evaluation of security measures will be
conducted on a finer grained scale. The advantage is that this allows showing combined
effects more accurately before scaling back to the overall scale of the threat scenario.
This method will use a scale of 30 calculation points for security measures. Note that
the grey levels used in the graphical scale are not supposed to represent risk levels, but
represent the overall effectiveness level in the threat scenario, as defined in Table 6-30
TABLE 6-30: EFFECTIVENESS CALCULATION SCALE
Each evaluation starts with the highest possible level of threat. This corresponds to non-
existent protection or 0 effectiveness points on the calculation scale. Security measures
applied to the threat scenario will reduce the level of threat. Each identified security
measure increases the protection against a specific attack, measured in points on the
calculation scale. The effectiveness level for a threat scenario is determined by the
combined effectiveness points for all identified security measures.
In this regard, anything that is able to reduce the level of threat (or provides some
protection) should be regarded as a security measure.
The effectiveness points assigned to a security measure are specific to the evaluated
threat scenario and its combination of multiple security measures. A security measure
may already have a basic capability identified in the security measure characterization
activity. The effectiveness with regard to the specific circumstances of the threat
scenario needs to be determined based on the basic capability of the security measure.
Example: A security measure may be designed to prevent against attacks on the
confidentiality of a target. Such a security measure may have a high capability of
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