C.22 - Verify that the device cannot be downgraded to old versions (anti-rollback) of valid firmware.
What is the purpose of this? In what scenario does this offer protection? Is this supposed to protect against accidental installation of old firmware, of a user hacking his own device, or of an attacker installing old firmware and then exploiting a vulnerability in it? Isn't the device already totally compromised if the attacker can install old firmware?