Secure IDS Offloading with Nested Virtualization and Deep VM Introspection

Abstract

To securely execute intrusion detection systems (IDSes) for virtual machines (VMs), IDS offloading with VM introspection (VMI) is used. In semi-trusted clouds, however, IDS offloading inside an untrusted virtualized system does not guarantee that offloaded IDSes run correctly. Assuming a trusted hypervisor, secure IDS offloading has been proposed, but there are several drawbacks because the hypervisor is tightly coupled with untrusted management components. In this paper, we propose a system called V-Met, which offloads IDSes outside the virtualized system using nested virtualization. Since V-Met runs an untrusted virtualized system in a VM, the trusted computing base (TCB) is separated more clearly and strictly. V-Met can prevent IDSes from being compromised by untrusted virtualized systems and allows untrusted administrators to manage even the hypervisor. Furthermore, V-Met provides deep VMI for offloaded IDSes to obtain the internal state of target VMs inside the VM for running a virtualized system. We have implemented V-Met in Xen and confirmed that the performance of offloaded legacy IDSes was comparable to that in traditional IDS offloading.