Smartphone usage has been continuously increasing in recent years. Moreover, smartphones are often used for privacysensitive tasks, becoming highly valuable targets for attackers. They are also quite different from PCs, so that PCoriented solutions are not always applicable, or do not offer comprehensive security. We propose an alternative solution, where security checks are applied on remote security servers that host exact replicas of the phones in virtual environments. The servers are not subject to the same constraints, allowing us to apply multiple detection techniques simultaneously. We implemented a prototype of this security model for Android phones, and show that it is both practical and scalable: we generate no more than 2KiB/s and 64B/s of trace data for high-loads and idle operation respectively, and are able to support more than a hundred replicas running on a single server. Categories and Subject Descriptors D.2.0 [General]: Protection mechanisms General Terms Design, Se...