Intel® SGX SDK Edger8r and Intel® Software Guard Extensions Platform Software Component

Summary:

CVE-2018-3626: The Edger8r tool in the Intel® Software Guard Extensions (SGX) Software Development Kit (SDK) before version 2.1.2 (Linux) and 1.9.6 (Windows*) may generate code that is susceptible to a side channel attack, potentially allowing a local user to access unauthorized information.

CVE-2017-5736: An elevation of privilege in Intel® Software Guard Extensions Platform Software Component before 1.9.105.42329 allows a local attacker to execute arbitrary code as administrator.

Description:

CVE-2018-3626: Recently it was reported that the Edger8r Tool, a software component of the Intel® Software Guard Extensions (SGX) Software Development Kit (SDK), may generate C source code potentially leading to a software based side-channel vulnerability.

Exposure of the vulnerability is limited to enclaves produced by developers who use the ‘string’ attribute or the ‘sizefunc’ attribute in the Edger8r Enclave Definition Language (EDL) syntax. When these attributes are used, and the resultant code is compiled into an SGX enclave, then that enclave may be exposed to a side-channel which could reveal sensitive data within the enclave. The actions outlined in this document should be followed to help minimize potential impacts.

The issue has the following Computer Vulnerability Scoring System (CVSS) rating

• 4.0 Medium CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVE-2017-5736: An elevation of privilege in Intel® Software Guard Extensions Platform Software Component before 1.9.105.42329 allows a local attacker to execute arbitrary code as administrator.

• 8.2 High CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Affected products:

CVE-2018-3626: Products developed with Intel® SGX SDK before version 2.1.2 (Linux) and 1.9.6 (Windows*)

CVE-2017-5736: Intel® Software Guard Extensions Platform Software Component before 1.9.105.42329

Recommendations:

CVE-2018-3626: Intel recommends that SGX developers, ISVs, and other affected parties review the information below, and undertake the related actions necessary to enhance their platform security.

• Update Intel® SGX SDK to version 2.1.2 (Linux Hotfix release) or 1.9.6 (Windows* SDK & PSW). Intel released the updated SDKs, beginning March 16, 2018. Use of the most current SGX SDK ensures the most up to date support for SGX and its applications.
• Developers should recompile and re-issue their enclaves with the updated Intel SGX SDK which became available on March 16, 2018 for Windows* and Linux.
• If an SGX enclave developer is using the ‘string’ and/or ‘sizefunc’ attributes in their enclave interface, the developer should review the technical guidance and determine whether they should rebuild enclave projects using the updated SDK.
• Additional guidance can be found in the whitepaper “Intel® Software Guard Extensions (SGX) SW Development Guidance for Potential Edger8r Generated Code Side Channel Exploits”.
• An updated “Intel® Software Guard Extensions (SGX) SW Development Guidance for Potential Bounds Check Bypass (CVE-2017-5753) Side Channel Exploits” has also been released based on changes made to the EDL syntax by this issue.
• Developers implementing their own SDK should review the documentation and code changes issued with the Intel SGX SDK for Linux.

If attestation is used

One way to ensure that SGX platforms are up to date is through the process of attestation. The attestation process verifies that the platform is a valid SGX platform and the platform components meet a defined set of security requirements. In addition, the attestation process enables the application provider to verify the security version of the application.

CVE-2017-5736: Intel highly recommends that developers and users update to Intel® Software Guard Extensions Platform Software Component version 1.9.105.42329 or later.

For Windows* 10 users run Windows* update and version 1.9.105.42329 will be updated.

For developers an updated client has been posted here: <https://software.intel.com/en-us/sgx-sdk/download&gt;

Acknowledgements:

Intel would like to thank Jo Van Bulck, Frank Piessens, and Raoul Strackx of Ku Leuven University for reporting CVE-2018-3626 and working with us on coordinated disclosure.

Intel would like to thank employee Michael N. Henry (DCG Red Team) for CVE-2017-5736.

Intel would also like to thank employees Kekai Hu, Ke Sun, Henrique Kawakami and Rodrigo Branco for CVE-2018-3626 and CVE-2017-5736.