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Computer Meteorology: Monitoring Compute Clouds Lionel Litty H. Andres′ Lagar-Cavilla Dept. of Computer Science University of Toronto Abstract Cloud computing environments allow customers to ex-ecute arbitrary code on hardware owned by a cloud provider. While cloud providers use virtualization to en-sure isolation between customers, they face additional security challenges. Malicious customers may leverage the provider’s hardware to launch attacks, either from VMs they own or by compromising VMs from benign customers. These attacks can damage the provider’s rep-utation and ability to serve other customers. In this paper we show that while cloud providers can use introspection to monitor customer VMs and detect malicious activity, it must be used with care since existing introspection tech-niques are based on assumptions that do not hold in cloud environments. 1 Introduction A virtual machine monitor (VMM) decouples OS images from the hardware they run on, enabling useful capa-bilities such as moving virtual machines (VM) between hosts, consolidating several underutilized VMs onto a single host, and the ability to checkpoint/rollback VMs. The availability of such capabilities has lowered data center costs immensely. Recently, it has also made pos-sible one of the many forms of cloud computing, some-times referred to as Infrastructure as a Service, in which customers execute their OS images on hardware rented from cloud providers such as Amazon’s EC2 service, GoGrid or Mosso. By shifting the burden of infrastruc-ture ownership and maintenance to the provider, cloud computing allows subscribers to scale their applications and leverage large pools of resources while only covering costs proportional to their actual resource usage. While enticing, there remain significant obstacles to this vision. In a recent survey of 244 IT executives and CIOs, security was ranked as the number one challenge facing cloud computing [5]. Cloud computing intro