Attacking And Defending: Bios

: Open-source tools like CHIPSEC allow administrators to test their systems for known vulnerabilities, such as improperly protected S3 boot scripts or exposed SMI handlers. The Future: Open Source vs. Opaque Firmware

: 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. Attacking and Defending BIOS

: When a system "wakes up" from sleep (S3 state), it relies on a boot script to restore hardware configurations. Researchers have demonstrated that if these scripts are stored in unprotected memory (ACPI NVS), an attacker with OS-level access can modify them to execute arbitrary code before the OS kernel even re-initializes. : Open-source tools like CHIPSEC allow administrators to

: Using Graphics aperture Direct Memory Access (DMA), attackers can sometimes bypass memory protections to perform live analysis of SMM code that should otherwise be isolated. Defending the Root of Trust Secure Boot then extends this verification to the OS loader

: 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.