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New HyperThreading Flaw Affects Intel 6th And 7th Generation Skylake and Kaby Lake-Based Processors (hothardware.com)
MojoKid writes: A new flaw has been discovered that impacts Intel 6th and 7th Generation Skylake and Kaby Lake-based processors that support HyperThreading. The issue affects all OS types and is detailed by Intel errata documentation and points out that under complex micro-architectural conditions, short loops of less than 64 instructions that use AH, BH, CH or DH registers, as well as their corresponding wider register (e.g. RAX, EAX or AX for AH), may cause unpredictable system behavior, including crashes and potential data loss. The OCaml toolchain community first began investigating processors with these malfunctions back in January and found reports stemming back to at least the first half of 2016.
The OCaml team was able pinpoint the issue to Skylake's HyperThreading implementation and notified Intel. While Intel reportedly did not respond directly, it has issued some microcode fixes since then. That's not the end of the story, however, as the microcode fixes need to be implemented into BIOS/UEFI updates as well and it is not clear at this time if all major vendors have included these changes in their latest revisions.
The OCaml team was able pinpoint the issue to Skylake's HyperThreading implementation and notified Intel. While Intel reportedly did not respond directly, it has issued some microcode fixes since then. That's not the end of the story, however, as the microcode fixes need to be implemented into BIOS/UEFI updates as well and it is not clear at this time if all major vendors have included these changes in their latest revisions.
The goal of this report is to make the existence of Intel CPU backdoors a common knowledge and provide information on backdoor removal.
What we know about Intel CPU backdoors so far:
TL;DR version
Your Intel CPU and Chipset is running a backdoor as we speak.
The backdoor hardware is inside the CPU/Bridge and the backdoor firmware (Intel Management Engine) is in the chipset flash memory.
30C3 Intel ME live hack:
[Video] 30C3: Persistent, Stealthy, Remote-controlled Dedicated Hardware Malware
@21:43, keystrokes leaked from Intel ME above the OS, wireshark failed to detect packets.
[Quotes] Vortrag:
"the ME provides a perfect environment for undetectable sensitive data leakage on behalf of the attacker".
"We can permanently monitor the keyboard buffer on both operating system targets."
Backdoor removal:
The backdoor firmware can be removed by following this guide using the me_cleaner script.
Removal requires a Raspberry Pi (with GPIO pins) and a SOIC clip.
Decoding Intel backdoors:
The situation is out of control and the Libreboot/Coreboot community is looking for BIOS/Firmware experts to help with the Intel ME decoding effort.
If you are skilled in these areas, download Intel ME firmwares from this collection and have a go at them, beware Intel is using a lot of counter measures to prevent their backdoors from being decoded (explained below).
Useful links:
The Intel ME subsystem can take over your machine, can't be audited
REcon 2014 - Intel Management Engine Secrets
Untrusting the CPU (33c3)
Towards (reasonably) trustworthy x86 laptops
30C3 To Protect And Infect - The militarization of the Internet
30c3: To Protect And Infect Part 2 - Mass Surveillance Tools & Software
1. Introduction, what is Intel ME
Short version, from Intel staff:
Re: What Intel CPUs lack Intel ME secondary processor?
Amy_Intel Feb 8, 2016 9:27 AM
The Management Engine (ME) is an isolated and protected coprocessor, embedded as a non-optional part in all current Intel chipsets, I even checked with the engineering department and they confirmed it.
Long version:
ME: Management Engine
The Intel Management Engine (ME) is a separate computing environment physically located in the MCH chip or PCH chip replacing ICH.
The ME consists of an individual processor core, code and data caches, a timer, and a secure internal bus to which additional devices are connected, including a cryptography engine, internal ROM and RAM, memory controllers, and a direct memory access (DMA) engine to access the host operating system's memory as well as to reserve a region of protected external memory to supplement the ME's limited internal RAM. The ME also has network access with its own MAC address through the Intel Gigabit Ethernet Controller integrated in the southbridge (ICH or