SgxPectre Attacks: Leaking Enclave Secrets via Speculative Execution

SgxPectre Attacks: Leaking Enclave Secrets via Speculative Execution
Guoxing Chen, Sanchuan Chen, Yuan Xiao, Yinqian Zhang, Zhiqiang Lin, Ten H. Lai
(Submitted on 25 Feb 2018)

This paper presents SgxPectre Attacks that exploit the recently disclosed CPU bugs to subvert the confidentiality of SGX enclaves. Particularly, we show that when branch prediction of the enclave code can be influenced by programs outside the enclave, the control flow of the enclave program can be temporarily altered to execute instructions that lead to observable cache-state changes. An adversary observing such changes can learn secrets inside the enclave memory or its internal registers, thus completely defeating the confidentiality guarantee offered by SGX. To demonstrate the practicality of our SgxPectre Attacks, we have systematically explored the possible attack vectors of branch target injection, approaches to win the race condition during enclave’s speculative execution, and techniques to automatically search for code patterns required for launching the attacks. Our study suggests that any enclave program could be vulnerable to SgxPectre Attacks since the desired code patterns are available in most SGX runtimes (e.g., Intel SGX SDK, Rust-SGX, and Graphene-SGX).


MeltdownPrime and SpectrePrime: Automatically-Synthesized Attacks Exploiting Invalidation-Based Coherence Protocols

MeltdownPrime and SpectrePrime: Automatically-Synthesized Attacks Exploiting Invalidation-Based Coherence Protocols

Caroline Trippel, Daniel Lustig, Margaret Martonosi

The recent Meltdown and Spectre attacks highlight the importance of automated verification techniques for identifying hardware security vulnerabilities. We have developed a tool for synthesizing microarchitecture-specific programs capable of producing any user-specified hardware execution pattern of interest. Our tool takes two inputs: a formal description of (i) a microarchitecture in a domain-specific language, and (ii) a microarchitectural execution pattern of interest, e.g. a threat pattern. All programs synthesized by our tool are capable of producing the specified execution pattern on the supplied microarchitecture. We used our tool to specify a hardware execution pattern common to Flush+Reload attacks and automatically synthesized security litmus tests representative of those that have been publicly disclosed for conducting Meltdown and Spectre attacks. We also formulated a Prime+Probe threat pattern, enabling our tool to synthesize a new variant of each—MeltdownPrime and SpectrePrime. Both of these new exploits use Prime+Probe approaches to conduct the timing attack. They are both also novel in that they are 2-core attacks which leverage the cache line invalidation mechanism in modern cache coherence protocols. These are the first proposed Prime+Probe variants of Meltdown and Spectre. But more importantly, both Prime attacks exploit invalidation-based coherence protocols to achieve the same level of precision as a Flush+Reload attack. While mitigation techniques in software (e.g., barriers that prevent speculation) will likely be the same for our Prime variants as for original Spectre and Meltdown, we believe that hardware protection against them will be distinct. As a proof of concept, we implemented SpectrePrime as a C program and ran it on an Intel x86 processor, averaging about the same accuracy as Spectre over 100 runs—97.9% for Spectre and 99.95% for SpectrePrime.

Xen Security Advisory XSA-254 updated to V12 (on Spectre/Meltdown)

The XSA on Spectre/Meltdown has been updated again, with more info on ARM firmware:

Xen Security Advisory CVE-2017-5753,CVE-2017-5715,CVE-2017-5754 / XSA-254
version 12

Information leak via side effects of speculative execution


Corrections to ARM SP2 information:
* ARM 32-bit requires new firmware on some CPUs.
* Provide link to the ARM firmware page, accordingly.
* ARM 32-bit mitigations are complete for Cortex-A CPUs.
We do not have information for other ARM CPUs at this time.

Systems running all versions of Xen are affected. For SP1 and SP2, both Intel and AMD are vulnerable. Vulnerability of ARM processors to SP1 and SP2 varies by model and manufacturer. ARM has information on affected models on the following website. For SP3, only Intel processors are vulnerable. (The hypervisor cannot be attacked using SP3 on any ARM processors, even those that are listed as affected by SP3.) Furthermore, only 64-bit PV guests can exploit SP3 against Xen. PVH, HVM, and 32-bit PV guests cannot exploit SP3.

Coping with Spectre and Meltdown: What sysadmins are doing

Esther Schindler has a new article on Spectre and Meltdown for SysAdmins:

Coping with Spectre and Meltdown: What sysadmins are doing

The recent security vulnerabilities dumped a bunch of to-do items on system administrators’ desks. Feel like you’re alone? Here’s what other sysadmins have done so far, as well as their current plans and long-term strategy, not to mention how to communicate progress to management.!topic/discuss/OSk4U32ShGs

Microsoft Windows Analytics now helps assess Meltdown and Spectre protections

To help IT professionals everywhere, we have added new capabilities to our free Windows Analytics service1 to report the status for all the Windows devices2 that they manage. These new capabilities include:

Firmware Status – This insight provides details about the firmware installed on the device. Specifically, this insight reports if the installed firmware indicates that it includes the specific protections required. Initially, this status will be limited to the list of approved and available firmware security updates from Intel4. We will be adding other CPU (chipset) partners’ data as it becomes available to Microsoft.

Windows Analyitcs

Jon Masters FOSDEM2018 Keynote on Spectre/Meltodown uploaded



more on Spectre/Meltdown (updated)

Acknowledgements: Intel would like to thank Jann Horn with Google Project Zero for his original report and for working with the industry on coordinated disclosure. Intel would also like to thank the following researchers for working with us on coordinated disclosure. Moritz Lipp, Michael Schwarz, Daniel Gruss, Stefan Mangard from Graz University of Technology. Paul Kocher, Daniel Genkin from University of Pennsylvania and University of Maryland, Mike Hamburg from Rambus, Cryptography Research Division and Yuval Yarom from University of Adelaide and Data61. Thomas Prescher and Werner Haas from Cyberus Technology, Germany

Sigh, these days all global tech companies are now cyber arms manufacturers. 😦


a bit more on Spectre/Meltdown (updated)

AMD: Software techniques for managing speculation on AMD processors

Click to access Managing-Speculation-on-AMD-Processors.pdf


Speculative execution is a basic principle of all modern processor designs and is critical to support high performance hardware. Recently, researchers have discussed techniques to exploit the speculative behavior of x86 processors and other processors to leak information to unauthorized code * . This paper describes software options to manage speculative execution on AMD processors ** to mitigate the risk of information leakage. Some of these options require a microcode patch that exposes new features to software. The software exploits have recently developed a language around them to make them easier to reference so it is good to review them before we start discussing the architecture and mitigation techniques.


ARM (Linaro) on Meltdown and Spectre

Spoiler alert:

[…]This is the first part in a series of blog posts about Meltdown and Spectre. The intention here was to penetrate the whitepapers and give an easy to grasp overview of the attacks. In the upcoming blog post we will talk more about individual components, like OP-TEE, Linux kernel and other firmware.

GCC 7.3 released, with Spectre Variant2 for x86/ppc

Subject: GCC 7.3 Released
Date: Thu, 25 Jan 2018 10:41:30 +0100 (CET)

The GNU Compiler Collection version 7.3 has been released.

GCC 7.3 is a bug-fix release from the GCC 7 branch containing important fixes for regressions and serious bugs in GCC 7.2 with more than 99 bugs fixed since the previous release.

This release includes code generation options to mitigate Spectre Variant 2 (CVE 2017-5715) for the x86 and powerpc targets.

PS: Microsoft updated MSC earlier. I’m not sure about status of Intel C Compiler or ARM C compiler. CLang has some changes in the pipeline:


a bit more on Spectre/Meltdown

Intel: Root Cause of Spectre/Meltdown Reboot Issues Identified

January 22, 2018 […]We have now identified the root cause for Broadwell and Haswell platforms, and made good progress in developing a solution to address it. Over the weekend, we began rolling out an early version of the updated solution to industry partners for testing, and we will make a final release available once that testing has been completed. Based on this, we are updating our guidance for customers and partners: We recommend that OEMs, cloud service providers, system manufacturers, software vendors and end users stop deployment of current versions, as they may introduce higher than expected reboots and other unpredictable system behavior. For the full list of platforms, see the Security Center site.[…]

meltdown-spectre-bios-list: machine-readable list of vendor patches

Meltdown/Spectre BIOS/Firmware Updates list

This is a list of all products an manufacturers which patched BIOS/Firmware addressing the Meltdown and Spectre vulnerabilities. If you have better info please send pull requests. Why I did this? to have a parseable list for all my hardware

curl -s | grep “$(cat /sys/devices/virtual/dmi/id/board_name)”

windows – powershell 3.0 or above
$model = (Get-WmiObject -Class Win32_ComputerSystem -ComputerName . | Select-Object -Property Model).Model
$mainboard = (Get-WmiObject Win32_BaseBoard | Select-Object Product).Product
$list = (Invoke-WebRequest
$list.Split(“`n”) | Select-String “$model |$mainboard “




Spectre/Meltdown 007 humor