AMD has reportedly specified, but it hasn't been released yet updates to the general public for one security error which affects the AMD Secure processor.
This element, formerly known as AMD PSP (Platform Security Processor), is one chip-on-chip security system, similar to Management Engine (ME) of Intel.
Just like the processors Intel ME, and AMD Secure Processors are an integrated co-processor that sits alongside the actual AMD64 x86 CPU cores and features a separate processing system that is tasked with handling various security-related functions.
Cfir Cohen, a security researcher with the Google Cloud Security team, reports that he discovered a vulnerability in the AMD Secure Processor Trusted Platform Module (TPM).
TPM is a component for storing critical system data, such as passwords, certificates, and encryption keys, and is located in a "secure" environment and outside of AMD's most easily accessible cores.
"Through static analysis, we found a stack overflow in the EkCheckCurrentCert mode," says Cohen. The researcher claims that an attacker could use specially formatted certificates (EK certificates) to gain remote code execution rights in the AMD Secure processor, effectively violating the security it offers.
Cohen mentioned that some basic mitigation techniques, such as stack cookies, NX stack, and ASLR. To date, however, they have not been implemented in AMD's Secure Processor, making exploit very easy.
Intel Me ™ processors use a similar TPM, but Cohen does not say whether it is affected.
Google researcher reported defect to AMD in September and AMD told researcher in December that it has developed an update and is preparing for its release.
Coincidentally, in Reddit [1, 2], some have reported seeing a new option that allows AMD PSP to be disabled, but it is unclear whether this new option is related to the updates that AMD reports on Cohen's findings.
It should be noted that a PSP disable option is somewhat unique in the CPU world. For example, Intel never allowed the users to disable its secret partner, despite the long list of security flaws reported for that particular component.
Cohen's revelation of the AMD Secure Processor processor flaw came the same day that Google researchers revealed the details of the Meltdown and Specter defects that affect most of the world's CPUs.
Last November, Intel again provided updates for several similar weaknesses in Intel ME which allowed attackers to install rootkits and recover data from safe parts of Intel processors.
