This document provides security guidelines for preventing the unauthorized modification of BIOS firmware on PC client systems. This document focuses on current and future x86 and x64 desktop and laptop systems, although the controls and procedures could potentially apply to any system design. Likewise, although the guide is oriented toward enterprise-class platforms, the necessary technologies are expected to migrate to consumer-grade systems over time.
Unauthorized modification of BIOS firmware by malicious software constitutes a significant threat because of the BIOS’s unique and privileged position within the PC architecture. A malicious BIOS modification could be part of a sophisticated, targeted attack on an organization — either a permanent denial of service (if the BIOS is corrupted) or a persistent malware presence (if the BIOS is implanted with malware).