A tale of two worlds: assessing the vulnerability of enclave shielding runtimes

Research output: Chapter in Book/Report/Conference proceedingConference contribution


  • Jo Van Bulck
  • Abdulla Aldoseri
  • Frank Piessens

Colleges, School and Institutes

External organisations

  • imec-DistriNet, KU Leuven, Belgium


This paper analyzes the vulnerability space arising in Trusted Execution Environments (TEEs) when interfacing a trusted enclave application with untrusted, potentially malicious code. Considerable research and industry effort has gone into developing TEE runtime libraries with the purpose of transparently shielding enclave application code from an adversarial environment. However, our analysis reveals that shielding requirements are generally not well-understood in real-world TEE runtime implementations. We expose several sanitization vulnerabilities at the level of the Application Binary Interface (ABI) and the Application Programming Interface (API) that can lead to exploitable memory safety and side-channel vulnerabilities in the compiled enclave. Mitigation of these vulnerabilities is not as simple as ensuring that pointers are outside enclave memory. In fact, we demonstrate that state-of-the-art mitigation techniques such as Intel's edger8r, Microsoft's "deep copy marshalling", or even memory-safe languages like Rust fail to fully eliminate this attack surface. Our analysis reveals 35 enclave interface sanitization vulnerabilities in 8 major open-source shielding frameworks for Intel SGX, RISC-V, and Sancus TEEs. We practically exploit these vulnerabilities in several attack scenarios to leak secret keys from the enclave or enable remote code reuse. We have responsibly disclosed our findings, leading to 5 designated CVE records and numerous security patches in the vulnerable open-source projects, including the Intel SGX-SDK, Microsoft Open Enclave, Google Asylo, and the Rust compiler.


Original languageEnglish
Title of host publicationCCS '19
Subtitle of host publicationProceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security
Publication statusPublished - 6 Nov 2019
Event26th ACM SIGSAC Conference on Computer and Communications Security (CCS 2019) - London, United Kingdom
Duration: 11 Nov 201915 Nov 2019


Conference26th ACM SIGSAC Conference on Computer and Communications Security (CCS 2019)
CountryUnited Kingdom


  • Trusted execution, TEE, Intel SGX, memory safety, side-channels