As its complexity grows, securing a system is harder than it looks. Even with efficient security mechanisms, their configuration remains a complex task. Indeed, the current practice is the hand-made configuration of these mechanisms to protect systems about which we generally lack information. Cloud computing brings its share of new security concerns but it may also be considered as leverage to overcome these issues. In this paper, we discuss the key challenge of achieving global security of Cloud systems and advocate for a new approach: Model-Driven Orchestration. We present an implementation of this new approach called Security-Aware Models for Clouds and illustrate it on an industrial use-case.