What is Secure Boot?

D3 ยท Architecture  ยท  CompTIA Security+ SY0-701
Secure Boot is a UEFI (Unified Extensible Firmware Interface) security standard that ensures only cryptographically signed, trusted bootloaders and OS kernels can run during system startup.

How it works: UEFI firmware contains a database of trusted certificates. During boot, each component's signature is verified before execution. Unsigned or improperly signed software is blocked.

Protects against: bootkits, rootkits that load before the OS, evil maid attacks.
Secure Boot + TPM (measured boot) = full chain of trust from firmware to OS. Secure Boot prevents unauthorized boot code; measured boot detects if something changed. Together they provide pre-OS security. Required for Windows 11.
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