Beware of Boot Memory Corruption Vulnerability in UEFI Firmware

CVSScvssV3_1: 7.8

A new vulnerability has been discovered in UEFI firmware that could allow attackers to corrupt memory during the boot process. The vulnerability, tracked as CVE-2023-33017, has a CVSS score of 7.8 out of 10 indicating its potential impact.

UEFI (Unified Extensible Firmware Interface) is the standard interface between operating systems and firmware. It replaces the older BIOS firmware found on PCs and is responsible for initializing and testing hardware components during the boot process. The vulnerability is a memory corruption issue that occurs when running a “ListVars” test in the UEFI menu. This could allow an attacker to execute arbitrary code with elevated privileges before the operating system loads.

While details are limited, it seems a malicious actor with physical access could exploit this by booting to the UEFI menu and triggering the memory corruption via the vulnerable “ListVars” test. This could then give the attacker full control of the system at a low level before Windows or Linux has a chance to load protections. Sensitive data may be at risk or the system could be compromised for further attacks.

The best way to protect yourself is to ensure your UEFI firmware is kept up-to-date. Contact your device manufacturer to check if an update is available that resolves this vulnerability. Avoid enabling UEFI features you don’t need for normal use. And be wary of untrusted USB devices or CD/DVDs when booting, as they could carry code to exploit this pre-boot vulnerability. Staying vigilant with firmware updates is key to defending against these types of early-stage attacks.