About Startup Security Utility on a Mac with the Apple T2 Security Chip
Use Startup Security Utility to make sure your Mac always starts up from your designated startup disk and from a legitimate, trusted operating system at all times.
If you're using a Mac with the Apple T2 Security Chip, Startup Security Utility offers three features to help secure your Mac against unauthorised access: Firmware password protection, Secure Boot and the ability to set allowed boot media.
If you're using a Mac with Apple silicon, find out how to change security settings on a Mac with Apple silicon.
Open Startup Security Utility
Turn on your Mac, then press and hold Command (⌘)-R immediately after seeing the Apple logo. Your Mac will start up from macOS Recovery.
When you're asked to select a user you know the password for, select the user, click Next, then enter their administrator password.
When you see the macOS utilities window, choose Utilities > Startup Security Utility from the menu bar.
When you're asked to authenticate, click Enter macOS Password, then choose an administrator account and enter its password.
Set a firmware password
You can use a firmware password to prevent anyone who doesn't have the password from starting up from a disk other than your designated startup disk. To set a firmware password in Startup Security Utility, click Turn On Firmware Password, then follow the onscreen instructions. Learn more about firmware passwords.
You can also disallow booting from external or removable media to prevent even those who know the firmware password from starting up from such media.
Change Secure Boot settings
Use these settings to make sure your Mac always starts up from a legitimate, trusted operating system.
Full Security is the default setting and offers the highest level of security. This is a level of security previously only available on iOS devices.
During startup, your Mac verifies the integrity of the operating system (OS) on your startup disk to make sure it's legitimate. If the OS is unknown or can't be verified as legitimate, your Mac connects to Apple to download the updated integrity information it needs to verify the OS. This information is unique to your Mac and it ensures that your Mac starts up from an OS that is trusted by Apple.
If FileVault is enabled while your Mac is attempting to download updated integrity information, you'll be asked to enter a password to unlock the disk. Enter your administrator password, then click Unlock to finish the download.
If the OS doesn't pass verification:
macOS: An alert will inform you that a software update is required to use this startup disk. Click Update to open the macOS installer, which you can use to reinstall macOS on the startup disk. Or click Startup Disk and choose a different startup disk, which your Mac will also attempt to verify.
Windows: An alert will inform you that you need to install Windows with Boot Camp Assistant.
If your Mac can't connect to the internet, it will display an alert stating that an internet connection is required.
Check your internet connection, such as by choosing an active network fromin the menu bar. Then click Try Again.
Or click Startup Disk and choose a different startup disk.
Or use Startup Security Utility to lower the security level
During startup when Medium Security is turned on, your Mac verifies the OS on your startup disk only by making sure it has been properly signed by Apple (macOS) or Microsoft (Windows). This doesn't require an internet connection or updated integrity information from Apple, so it won't prevent your Mac from using an OS that's no longer trusted by Apple.
If the OS doesn't pass verification:
macOS: An alert will inform you that a software update is required to use this startup disk. Click Update to open the macOS installer, which you can use to reinstall macOS on the startup disk. This requires an internet connection. Or click Startup Disk and choose a different startup disk, which your Mac will also attempt to verify.
Windows: An alert informs you that you need to install windows with Boot Camp Assistant.
No Security doesn't enforce any of the above security requirements for your startup disk.
Set allowed boot media
Use this feature to control whether your Mac can start up from external or removable media. The default, most secure setting is to disallow it. If you attempt to boot from such media and you receive a warning that your security settings do not allow it, you can change the setting in Startup Security Utility.
Your Mac doesn't support booting from network volumes, whether you allow booting from external or removable media or not.