Abstract
In the public clouds, an adversary can co-locate his or her virtual machines (VMs) with others on the same physical servers to start an attack against the integrity, confidentiality or availability. The one important factor to decrease the likelihood of this co-location attack is the VMs placement strategy. However, a co-location resistant strategy will compromise the resources optimization of the cloud providers. The tradeoff between security and resources optimization introduces one of the most crucial challenges in the cloud security. In this work we propose a placement strategy allowing the decrease of co-location rate by compromising the VM startup time instead of the optimization of resources. We give a mathematical analysis to quantify the co-location resistance. The proposed strategy is evaluated against the abusing placement locality, where the attack and target VMs are launched simultaneously or within a short time window. Referring to EC2 placement strategy, the best co-location resistant strategy out of the existing public cloud providers strategies, our strategy decreases enormously the co-location attacks with a slight VM startup delay (relatively to the actual VM startup delay in the public cloud providers).