Security Assessment of Intel TDX with support for Live Migration

TL;DR

This paper reports on a security assessment of Intel TDX with support for live migration, revealing vulnerabilities that could compromise confidential computing environments and emphasizing the need for layered security measures.

Contribution

First comprehensive security evaluation of Intel TDX with live migration support, identifying critical vulnerabilities and providing insights for improving confidential computing security.

Findings

Discovered a vulnerability allowing full compromise of a TD by a VMM.

Identified four vulnerabilities enabling memory leaks to malicious VMM or TD.

Highlighted the importance of iterative security refinement and defense-in-depth strategies.

Abstract

In the second and third quarters of 2025, Google collaborated with Intel to conduct a security assessment of Intel Trust Domain Extensions (TDX), extending Google's previous review and covering major changes since Intel TDX Module 1.0 - namely support for Live Migration and Trusted Domain (TD) Partitioning (nested VMs within TDs). Intel provided guidance and support, including documentation and updated TDX 1.5 source code. Unlike the previous review, this time, we had access to a compute node capable of running TDX to develop a toolkit for live testing and Proof-of-Concept (PoC) generation. Furthermore, we integrated Gemini for analysis and NotebookLM to efficiently navigate complex specifications. This assessment resulted in the discovery of one vulnerability that enables a VMM to fully compromise a TD, and four vulnerabilities that enable a malicious VMM or TD to leak confidential memory of the Intel TDX Module. Several other security weaknesses and/or bugs were identified but not categorized as vulnerabilities despite having some impact on security. Beyond presenting the technical details of multiple bugs and vulnerabilities in this report, these findings underscore that confidential computing, like other security measures, requires iterative refinement and complementary security controls to harden it, in line with a defense-in-depth approach.