A Survey of the State of Cloud Security <s> Shared resources <s> Third-party cloud computing represents the promise of outsourcing as applied to computation. Services, such as Microsoft's Azure and Amazon's EC2, allow users to instantiate virtual machines (VMs) on demand and thus purchase precisely the capacity they require when they require it. In turn, the use of virtualization allows third-party cloud providers to maximize the utilization of their sunk capital costs by multiplexing many customer VMs across a shared physical infrastructure. However, in this paper, we show that this approach can also introduce new vulnerabilities. Using the Amazon EC2 service as a case study, we show that it is possible to map the internal cloud infrastructure, identify where a particular target VM is likely to reside, and then instantiate new VMs until one is placed co-resident with the target. We explore how such placement can then be used to mount cross-VM side-channel attacks to extract information from a target VM on the same machine. <s> BIB001 </s> A Survey of the State of Cloud Security <s> Shared resources <s> Cloud computing is expected to become a common solution for deploying applications thanks to its capacity to leverage developers from infrastructure management tasks, thus reducing the overall costs and services’ time to market. Several concerns prevent players’ entry in the cloud; security is arguably the most relevant one. Many factors have an impact on cloud security, but it is its multitenant nature that brings the newest and more challenging problems to cloud settings. Here, we analyze the security risks that multitenancy induces to the most established clouds, Infrastructure as a service clouds, and review the literature available to present the most relevant threats, state of the art of solutions that address some of the associated risks. A major conclusion of our analysis is that most reported systems employ access control and encryption techniques to secure the different elements present in a virtualized (multitenant) datacenter. Also, we analyze which are the open issues and challenges to be addressed by cloud systems in the security field. <s> BIB002
Understanding how data is stored and accessed in the cloud will help mitigate risks associated with sharing of resources. Encrypting data before storing it in the cloud can reduce the risk of information leakage. Conventional symmetric and asymmetric encryption algorithms can be used for this purpose. In cloud environments, it is also necessary to encrypt data in cache or memory to account for sniffing attacks by neighboring nodes. In the cloud environment, malicious parties can take advantage of the lack of isolation between tenants. In such cases, success of an attack depends on the ability of the attacker in determining co-residency of another instance BIB001 ). Inhibiting co-residency checks can thwart attacks like VM escape attacks and VM hopping attacks. Another threat faced because of shared environment is attacks on the hypervisor. These attacks can threaten the confidentiality of tenant data. One way of protecting the hypervisor is to hide the fact that the machine is a virtual machine BIB002 .