  This report summarizes the discussions and findings of the 2017 North
Atlantic Treaty Organization (NATO) Workshop, IST-153, on Cyber Resilience,
held in Munich, Germany, on 23-25 October 2017, at the University of
Bundeswehr. Despite continual progress in managing risks in the cyber domain,
anticipation and prevention of all possible attacks and malfunctions are not
feasible for the current or future systems comprising the cyber infrastructure.
Therefore, interest in cyber resilience (as opposed to merely risk-based
approaches) is increasing rapidly, in literature and in practice. Unlike
concepts of risk or robustness - which are often and incorrectly conflated with
resilience - resiliency refers to the system's ability to recover or regenerate
its performance to a sufficient level after an unexpected impact produces a
degradation of its performance. The exact relation among resilience, risk, and
robustness has not been well articulated technically. The presentations and
discussions at the workshop yielded this report. It focuses on the following
topics that the participants of the workshop saw as particularly important:
fundamental properties of cyber resilience; approaches to measuring and
modeling cyber resilience; mission modeling for cyber resilience; systems
engineering for cyber resilience, and dynamic defense as a path toward cyber
resilience.
