Attacking And Defending Bios -

The Basic Input/Output System (BIOS) and its modern successor, the Unified Extensible Firmware Interface (UEFI), represent the most critical layer of a computer's security. As the first code to execute upon power-on, a compromised BIOS grants an attacker "Ring -2" privileges, allowing them to subvert the operating system, bypass disk encryption, and remain persistent even after a hard drive replacement.

Modern BIOS attacks focus on vulnerabilities within the UEFI firmware, often targeting the transition phases of the boot process. Attacking and Defending BIOS

: Reducing the attack surface is critical. Platforms like DECAF perform "dynamic surgery" on UEFI binaries to remove unnecessary code without affecting performance, effectively hardening the firmware. The Basic Input/Output System (BIOS) and its modern

: Non-volatile storage (NVRAM) variables can sometimes be manipulated to bypass passwords or alter the Secure Boot policy. Tools like UEFI Tool and Universal-IFR-Extractor are used to reverse-engineer these modules and identify sensitive offsets. : Reducing the attack surface is critical

: Modern systems use Intel Boot Guard or AMD Hardware-Validated Boot to verify the digital signature of the BIOS before execution. Secure Boot then extends this verification to the OS loader.

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