  We model a vehicle equipped with an autonomous cyber-defense system in
addition to its inherent physical resilience features. When attacked, this
ensemble of cyber-physical features (i.e., ``bonware'') strives to resist and
recover from the performance degradation caused by the malware's attack. We
model the underlying differential equations governing such attacks for
piecewise linear characterizations of malware and bonware, develop a discrete
time stochastic model, and show that averages of instantiations of the
stochastic model approximate solutions to the continuous differential equation.
We develop a theory and methodology for approximating the parameters associated
with these equations.
