WASMBOX: A Lightweight Wasm-based Runtime for Trustworthy Multi-Tenant Embedded Systems

Enabling multi-tenancy on edge devices is crucial for maximizing resource utilization, enhancing scalability, and reducing costs. However, it introduces the challenge of maintaining tenant isolation, preventing adverse inter-tenant effects and unauthorized resource access. Traditional multi-tenant solutions often struggle in embedded systems due to resource constraints, and current lightweight approaches suffer from performance, portability, and tenant density issues. We propose WASMBOX, a novel solution for sandboxing applications in multi-tenant embedded systems. It leverages WebAssembly to offer strong isolation, small attack surface, high portability, efficient resource usage, and near-native performance. Our system ensures both attack prevention and detection, using a patched WebAssembly System Interface for safe system call execution, and a monitoring layer for anomaly detection. Additionally, WASMBOX uses a Trusted Execution Environment for further isolating applications against escaping tenants and attesting to the integrity of WebAssembly applications. We validated our solution in a real-world case study with the SpaceApplications company, aiming to adopt a multi-tenant model for its ISS-based micro-gravity research facility. The experimental evaluation compared WASMBOX with approaches relying on VMs, containers, and microkernel-based VMs. The obtained results show that WASMBOX has the lowest resource usage, the highest tenant density, the second lowest startup (preceded by microkernels), and execution time (preceded by containers).