Evil maid attacks. Trusted boot is necessary to prevent the modification of unencrypted boot code like bootloader + kernel + initrd. Modified boot code could potentially steal the master key for the root volume while it gets entered. Also rootkits that inject below the os.
Sadly it is actually one of the biggest security features that modern computers have
What kind of attack does it actually protect against?
Evil maid attacks. Trusted boot is necessary to prevent the modification of unencrypted boot code like bootloader + kernel + initrd. Modified boot code could potentially steal the master key for the root volume while it gets entered. Also rootkits that inject below the os.
Rootkits