In devices with secure boot, why is an anti-rollback mechanism needed?

Answer: C. Older vulnerable software versions also carry valid signatures, so reverting to them enables attacks

The vendor has signed older releases legitimately too, so signature checks alone would still boot an old version reinstalled after a vulnerability was found. Software therefore carries a version number, and the chip records in write-once storage such as eFuses a minimum version below which it refuses to boot. Advancing this number with each update prevents rollback to old versions.

• A. New versions are signed too.
• B. It is not about speed.
• C. Correct. Version numbers kept in unchangeable storage are compared.