Malicious softwares or malwares for short have become a major security threat. While originating in criminal behavior, their impacts are also influenced by the decisions of legitimate end users. Getting agents in the Internet, and in networks in general, to invest in and deploy security features and protocols is a challenge, in particular because of economic reasons arising from the presence of network externalities. In this paper, the authors focus on the question of incentive alignment for agents of a large network towards a better security. They start with an economic model for a single agent, that determines the optimal amount to invest in protection.