Virtualization software security

Both public and private clouds use a hypervisor to host the virtual machines that are launched by cloud users. For example, AWS uses the Citrix XEN hypervisor, whereas OpenStack uses the KVM hypervisor by default.  Hardware and operating system virtualization allows the cloud provider to share the hardware across several guest virtual machines without interfering with each other. In other words, multiple virtual machines running different operating systems can run on the same hardware simultaneously. But running several virtual machines on a single physical host has its own set of risks.  

Public cloud customers who launch virtual machines have no visibility to this hypervisor or any other virtualization software that the cloud uses. On the other hand, in a private cloud, the administrator has more control over the hypervisor used. The hypervisor is a software just like any other software running on the system. If an attacker becomes aware of any loopholes...