Microsoft Releases LiteBox: Rust-based Sandboxing Library OS

Microsoft has introduced LiteBox, its new library OS for sandboxing Linux applications. The open-source project, released under the MIT license, uses Rust as its programming language and aims to significantly minimize the attack surface through greatly reduced interfaces to the host system.

LiteBox differs from traditional sandboxing approaches through its library OS approach. While classic virtual machines bring a complete kernel and containers share the kernel with the host system, LiteBox relies on a modular architecture with so-called North and South interfaces. The North interface is based on nix and rustix and offers POSIX-like system calls in Rust. The South interface connects various host platforms to the library OS. LiteBox has been designed for execution in both kernel and non-kernel modes.

Support for Confidential Computing

The architecture allows unmodified Linux programs to be executed under Windows, Linux applications to be used in a sandbox on Linux systems, or programs to run on AMD SEV SNP (Secure Encrypted Virtualization Secure Nested Paging). LiteBox also supports the integration of OP-TEE (Open Portable Trusted Execution Environment) on Linux systems. This makes the project primarily suitable for confidential computing scenarios in cloud environments. A typical use case would be, for example, running application code in a multi-tenant cloud environment where maximum isolation between different workloads is required.

The decision for Rust as the implementation language follows the trend towards greater memory safety in system-level software. Rust eliminates entire classes of security vulnerabilities such as buffer overflows through its ownership model, without relying on garbage collection. Microsoft is already using Rust for driver development and last year introduced Edit, a new open-source editor for the command line, written entirely in Rust. At the end of 2025, Microsoft even had to address the rumor that all C/C++ code was to be migrated to Rust by 2030.

Still in Experimental Stage

Interested users should note that LiteBox is still under active development. The APIs and interfaces may still change, and a stable release is not yet available. Microsoft recommends on GitHub therefore to wait for a stable version for production use or to plan for corresponding adjustments. The project is currently primarily aimed at developers who want to experiment with new sandboxing concepts.

Compared to alternatives such as gVisor from Google, which intercepts system calls in user space, or Firecracker from Amazon, which uses Rust-based micro-VMs, LiteBox promises particularly low overhead through its library OS architecture. However, concrete performance benchmarks are not yet available. Kata Containers, which provides VMs for Kubernetes, addresses similar use cases but relies on a different technical basis.

LiteBox currently officially supports AMD SEV SNP as a hardware platform and Linux and Windows as host operating systems. Whether Microsoft plans to integrate LiteBox into Azure or the Windows Subsystem for Linux is not known.

(fo)