  This paper presents a mapping framework for design factors and implementation
process for building credible Industrial Control Systems (ICS) security
testbeds. The resilience of ICSs has become a critical concern to operators and
governments following widely publicised cyber security events. The inability to
apply conventional Information Technology security practice to ICSs further
compounds challenges in adequately securing critical systems. To overcome these
challenges, and do so without impacting live environments, testbeds for the
exploration, development and evaluation of security controls are widely used.
However, how a testbed is designed and its attributes, can directly impact not
only its viability but also its credibility as a whole. Through a combined
systematic and thematic analysis and mapping of ICS security testbed design
attributes, this paper suggests that the expertise of human experimenters,
design objectives, the implementation approach, architectural coverage, core
characteristics, and evaluation methods; are considerations that can help
establish or enhance confidence, trustworthiness and acceptance; thus,
credibility of ICS security testbeds.
