Scalable Attestation of Virtualized Execution Environments in Hybrid- and Multi-Cloud

Abstract: Existing attestation mechanisms lack scalability and support for heterogeneous virtual execution environments (VEEs), such as virtual machines and containers executed inside or outside hardware isolation on different vendors' hardware in clouds managed by various organizations. To overcome these limitations, hardware vendors and cloud providers implement proprietary mechanisms (Intel DCAP, Amazon NitroTPM, Google Titan) to support their offerings. However, due to their plurality, the attestation becomes cumbersome because it increases maintenance and integration costs and reduces portability required in hybrid- and multi-cloud deployments. We introduce WAWEL, a framework that enables scalable attestation of heterogeneous VEEs. WAWEL can be plugged into existing hardware-specific attestation mechanisms, offering a unified interface. WAWEL supports the widely adopted trusted platform module (TPM) attestation standard. We implemented a prototype and integrated it with three different VEEs. It supports runtime integrity attestation with Linux integrity measurement architecture (IMA) and legacy applications requiring zero-code changes. The evaluation demonstrated that the WAWEL prototype achieves very good performance and scalability despite the indirections between the VEE and hardware root of trust.