Bluetooth devices already registered after clean installation

[olfab]

Dear all,

macOS irritated me: I made a clean installation of macOS 10.14.4 on my MacBook Pro 2018. This includes erasing the ssd device in disk utils and starting the installation using alt + cmd + r which is supposed to load the latest compatible version of macOS available. There are no backups to icloud.

Right after the installation my magic mouse and beats x were already registered. I did not have to pair them again. I called up apple support and have been told that this information is stored in a portion of the ssd that gets not erased during an erase with disk utils.

And this irritates me: Couldn't a virus or malware store itself in this portion of the ssd?

Best regards,
Fabian

 

[coldwaves]

Yes, it has been this way since at least OS X Mavericks and maybe earlier. Regardless how your clean install macOS, either from the web or using a bootable USB, the paired Bluetooth devices remain. You have to manually unpair them before fresh installation of macOS to not have them registered after the fresh macOS install. To remove the paired devices and reset them, you can press Shift+Option and click the Bluetooth icon on the menu bar, select the device you want to remove, and choose factory reset.

 

[olfab]

Thanks for your answer coldwaves.

Do you know of any other data stored that permanently?

macOS exposing unexpected behavior gives me a bad sensation.

 

[coldwaves]

Thanks for your answer coldwaves.

Do you know of any other data stored that permanently?

macOS exposing unexpected behavior gives me a bad sensation.

I am not aware of any other information being stored after fresh installation other than the paired bluetooth device. It looks like everything else has to be re-set up after a clean install. But I'm in no way an expert in this.

 

[treekram]

I don't think it's likely that there's some secret file somewhere on the SSD that stores the Bluetooth device information. I don't regularly use Bluetooth devices so I haven't tested this out, but look at the following article:
https://www.makeuseof.com/tag/bluetooth-not-available-troubleshooting-mac-connectivity-issues/

To delete your previous Bluetooth devices, try the following:
1) Make sure the preferences file for Bluetooth hasn't somehow gotten back on your disk (via a migration tool) - this is explained in the "Bluetooth Not Available" section of the article above.
2) Reset the bluetooth module as explained in the "Nuke Your Bluetooth Module" in the article above.
3) Reset NVRAM. This is the non-volatile memory on your Mac which stores certain preferences.
https://support.apple.com/en-us/HT204063

If the Bluetooth device information still remains, you can try completely erasing the disk (this isn't available in the Disk Utility app in later OS versions) to see if indeed there is some other place where the device information is stored. You would use the diskutil command-line program to do this.

 

[drugones]

Have you got other Apple devices ?

Apple devices seems to share Bluetooth connection information, so even after full erase, your laptop will sync back the Bluetooth data from other devices.

 

[Bornee35]

another option. is the slave device in question already has the handshake info stored, and is broadcasting to the known BD_ADDR.

Side note: formatting a drive doesn't erase all data. A single pass just removes the hierarchy. Multiple passes need to be done to ensure a full wipe. Just like the bathroom

 

[Brian33]

I'm guessing, but the pairing info might have been kept in NVRAM. This is memory that's retained even through power-down and is not in the disk or SSD that makes up your "storage," so it wouldn't get wiped with a re-format.

You can see what's in NVRAM with this Terminal command:
nvram -p

I see there is some info in "bluetoothInternalControllerInfo" and "bluetoothActiveControllerInfo" on my machine. In treekram's post above is a link showing how to clear NVRAM. (Also it appears you can do it with the nvram command.)

 

[olfab]

I assume, the contents of the ssd may not be erased securely but is at least not accessible since FileVault was activated before.

I checked the nvram. I found the term "bluetooth" but the rest was cryptic. And I found my name. Thus, I should not forget to erase the nvram when selling this machine.