A data security system and method protects stored data from unauthorized access. According to one aspect of the invention, a client computing device communicates periodically with a server. If communications is note established between the client and the server for a selected activation interval and a subsequent grace period, the data is determined to be lost and, programmed security rules are automatically executed. The server with which the client computer device communicates includes one server located inside the firewall of a particular organization, or a mirror server located outside the firewall, and thereby allow for the re-setting of the activation interval when the client is properly outside of the firewall through communication with the mirror server, as well as the to provide command an control over a lost or stolen client by pushing updated rules if communication is subsequently attempted with the mirror server.