AMD is going to patch UEFI SMM callout privilege escalation flaw

AMD is going to release patches for a flaw affecting the System Management Mode (SMM) of the Unified Extensible Firmware Interface (UEFI).

AMD recently announced that it was preparing patches for an SMM Callout Privilege Escalation vulnerability, tracked as CVE-2020-12890, that affects the System Management Mode (SMM) of the Unified Extensible Firmware Interface (UEFI).

The vulnerability was discovered by the security researcher Danny Odler, it resides in the AMD’s Mini PC could allow attackers to manipulate secure firmware and execute arbitrary code.

“AMD is aware of new research related to a potential vulnerability in AMD software technology supplied to motherboard manufacturers for use in their Unified Extensible Firmware Interface (UEFI) infrastructure and plans to complete delivery of updated versions designed to mitigate the issue by the end of June 2020.” reads the AMD’s announcement.

“The targeted attack described in the research requires privileged physical or administrative access to a system based on select 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.”

The issue could be exploited by attackers only if they have privileged physical or administrative access to a system that includes one of the affected AMD notebook or embedded processors.

If these pre-conditions are met, an attacker could potentially manipulate the AMD Generic Encapsulated Software Architecture (AGESA) to execute arbitrary code without being detected by the operating system.

AMD pointed out that only certain processors released between 2016 and 2019 are affected by the vulnerability.

The chip vendor has already delivered most of the updated versions of AGESA to its partners.

AMD recommends users to kept their systems updated by installing the latest patches.

“SMM is the most privileged code that can execute on x86 CPU thus allowing to attack any low level component including Kernel and Hypervisor.” reads the analysis published by Odler.

Odler discovered three vulnerabilities in SMM, the CVE-2020–14032 flaw was addressed in early June, the remain ones are yet to be addressed.

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Pierluigi Paganini

(SecurityAffairs – hacking, chips)

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