Security of Safety Important I&C Systems - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 270

Security Controls: The management, opera-
tional, and technical controls (i.e., safeguards or
countermeasures) prescribed for an information
system to protect the confidentiality, integrity,
and availability of the system and its information.
Threat: Any circumstance or event with the
potential to adversely impact agency operations
(including mission, functions, image, or reputa-

tion), agency assets, or individuals through an
information system via unauthorized access, de-
struction, disclosure, modification of information,
and/or denial of service.
Vulnerability: Weakness in an information
system, system security procedures, internal con-
trols, or implementation that could be exploited
or triggered by a threat source.