1 -This paper presents a framework to enhance a system's survivability to thwart malicious attacks and to continuously provide critical services to users. We focus on two key survivability elements: strategy and tactic. The latter further includes a set of activities and operations. We show how survivability activities are developed in light of tactics to implement the chosen survivability strategies in face of malicious attacks. An example of military command and control system is presented, where a set of survivability activities are specified to carry out two strategies: dynamic system reconfiguration and transparent system repairs. An architectural model is proposed to facilitate system design in building survivable systems.