Security games are characterized by multiple players who strategically adjust their defenses against an abstract attacker, represented by realizations of nature. The defense strategies include both actions where security generates positive externalities and actions that do not. When the players are assumed to be risk averse, market insurance enters as a third strategic option. We formulate a one-shot security game with market insurance, characterize its pure equilibria, and describe how the equilibria compare to established results. Simplifying assumptions include homogeneous players, fair insurance premiums, and complete information except for realizations of nature. The results add more realism to the interpretation of analytical models of security games and might inform policy makers on adjusting incentives to improve network security and foster the development of a market for cyber-insurance.