Availability Analysis of an Intrusion Tolerant Distributed Server System With Preventive Maintenance

We consider availability models of an intrusion tolerant system, and investigate quantitative effects of preventive maintenance based on security patch releases. The stochastic behavior of the system is analyzed through an embedded Markov chain approach. More specifically, two semi-Markov models are formulated in continuous-time, and discrete-time scales. We derive the optimal preventive patch management times maximizing the steady-state system availability in respective models, and evaluate both the system availability, and the mean time to security failure. Numerical examples are presented for illustrating the optimal preventive maintenance policies, and performing sensitivity analysis of model parameters.

Acronym

CIDTS

Cooperative intrusion detection and tolerance system

COTS

Commercial-off-the-shelf

CTSMM

Continuous-time semi-Markov model

DHR

Decreasing hazard rate

DoS

Denial-of-service

DTMC

Discrete-time Markov chain

DTSMM

Discrete-time semi-Markov model

EMC

Embedded Markov chain

IHR

Increasing hazard rate

MTTSF

Mean time to security failure

OS

Operating system

P2P

Peer-to-peer

PPMT

Preventive patch management time

SITAR

Scalable intrusion tolerant architecture

SMP

Semi-Markov Process