Quantitative Assessment of Operational Security: Models and Tools *

摘要: Abstract This paper proposes a novel approach to help computing system administrators inmonitoring the security of their systems. is based on modeling thesystem as privilege graph exhibiting operational vulnerabilities and ontransforming this into Markov chain corresponding all possiblesuccessful attack scenarios. A set tools has been developed generateautomatically Unix system, transform it thecorresponding compute characteristic measures theoperational security.Keywords: quantitative evaluation, graph, 1. Introduction Computing relies mostly users, operators administrators, eventhe best designed if badly operated, would be unsecure. Most authentication andprotection mechanisms can diverted by malicious or careless then allowing possibleintruders perform breaches. not surprising since most users are lessinterested in than efficiency, flexibility cooperation with other users.A scrupulous administrator should try maintain for his systemwith least incidence user operation. It thus tremendously important assess thesecurity level monitor evolution withrespect configuration modifications, application operation changes andenvironment evolution.This develops an evaluate systems.Examples taken from Unix™ systems, but could extended otheroperating systems distributed well. Section 2 shows how model acomputing way that exploited possible