Since the Intel CSME subsystem has special tools for intercepting any data passing through a USB controller (the so-called USB-Redirection), an attacker using this vulnerability could launch a special malicious code on Intel CSME that will read keystrokes (keylogger). In an email responding to a question about the extent of the potential damage caused by the exploit and how the exploit worked, Ermolov wrote: Because exploits allow the modification of firmware, attackers could carry out other nefarious actions. The larger worry is that, because this vulnerability allows a compromise at the hardware level, it destroys the chain of trust for the platform as a whole.” Advertisementīesides the Trusted Platform Module, attackers who successfully exploit the flaw can bypass security protections provided by Intel’s Enhanced Privacy ID (EPID) (which provides on-chip encryption capabilities) and digital rights management protections for proprietary data. It might also be possible to extract the chipset encryption key, which is identical on each chipset generation. “The problem is not only that it is impossible to fix firmware errors that are hard-coded in the mask ROM of microprocessors and chipsets. “This vulnerability jeopardizes everything Intel has done to build the root of trust and lay a solid security foundation on the company's platforms,” Mark Ermolov, lead specialist of OS and hardware security at security firm Positive Technologies wrote in a post detailing the bug. Jeopardizing Intel’s root of trustīecause the flaw resides in the CSME mask ROM, a piece of silicon that boots the very first piece of CSME firmware, the vulnerability can’t be patched with a firmware update. That failure creates a window of opportunity for other chip components, such as the Integrated Sensor Hub, to execute malicious code that runs very early in the boot process with the highest of system privileges. The bug stems from the failure of the input-output memory management unit-which provides protection preventing the malicious modification of static random-access memory-to implement early enough in the firmware boot process. Often abbreviated as CSME, this feature implements the firmware-based Trusted Platform Module used for silicon-based encryption, authentication of UEFI BIOS firmware, Microsoft System Guard and BitLocker, and other security features. The flaw resides in the Converged Security and Management Engine, a subsystem inside Intel CPUs and chipsets that’s roughly analogous to AMD’s Platform Security Processor. While Intel has issued patches to lessen the damage of exploits and make them harder, security firm Positive Technologies said the mitigations may not be enough to fully protect systems. Virtually all Intel chips released in the past five years contain an unfixable flaw that may allow sophisticated attackers to defeat a host of security measures built into the silicon.
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