AMD preparing to patch for SMM.

AMD last week said it was preparing patches for a vulnerability affecting the System Management Mode (SMM) of the Unified Extensible Firmware Interface (UEFI) shipped with systems that use certain notebook and embedded processors.

This vulnerability is one of the three issues reported in April, allowing an attacker to manipulate secure firmware and execute arbitrary code while avoiding detection.

An attacker looking to exploit the vulnerability needs privileged physical or administrative access to a system that includes one of the affected AMD notebook or embedded processors.

If this level of access is acquired, an attacker could potentially manipulate the AMD Generic Encapsulated Software Architecture (AGESA) to execute arbitrary code undetected by the operating system.

AMD, which has already delivered most of the updated versions of AGESA to its partners, says that only certain processors released between 2016 and 2019 are affected. The company advises users to ensure their devices are kept updated with the latest patches.

SMM is the most privileged code that can execute on x86 CPU, and that it can be abused to target Kernel, Hypervisor, and other low level components as well.