Secure Offloading of Intrusion Detection Systems from VMs with Intel SGX

Abstract

Virtual machines (VMs) inside clouds need to be monitored using intrusion detection systems (IDS). Since host-based IDS can be easily disabled by intruders, IDS offloading with VM introspection (VMI) is used to securely run IDS outside a target VM. However, offloaded IDS can be still attacked because it runs on top of a vulnerable operating system (OS). Various systems have been proposed to protect offloaded IDS, but no systems provide an appropriate execution environment to IDS. This paper proposes SGmonitor for enabling the secure execution of IDS offloaded from VMs inside clouds using Intel SGX. SGmonitor executes IDS in SGX enclaves and preserves confidentiality and integrity. It provides secure VMI for memory and storage by using encryption and integrity checking. To make the development of offloaded IDS easier, it provides the in-kernel API to in-enclave IDS and enables transparent access to OS data in VMs. We have implemented SGmonitor in Xen with SGX support and showed that the overhead of in-enclave IDS was 31% in compensation for much stronger security.