Guest user

One reason it is like that is so a thief CAN access the system so Find My Mac can actually Find Your Mac. If the thief can access the system and go to the NET Find My Mac doesn't work.

Well once it is stolen it is no longer yours. Possession is 99% of ownership.

You do realize the above was a joke don't you?

Try this. Login to that Guest users account and see if you can copy your files to an external drive without having to type in your Admin password. If you can then you are right. If you can't then there is nothing to worry about. That is unless the thief knows your Admin password.

In your own account highlight the external drive and press CMD i.

Scroll to the bottom of the properties box and untick the ignore permissions box.

Confirm that your account is in the list of accounts and you have read/write permissions, apply the changes.

Test with your account and a guest account.

I suggest you test this with a spare external drive, could be a USB pen drive, and confirm that this is the outcome you expect and it will work correctly with your files.

You should not be able to read the your user account on the Macintosh Drive from the guest account, the folders should have a red no access icon on them.

sparks2 wrote:

Next we'll only be using windows.

If you think Windows is gonna prevent the thief from grabbing all of your data, well, good luck.

As LowLuster explained, Guest account is part of the activation of iCloud Find my Mac.

If you want to be sure that no one would get your data off your drives you must use encryption. OS X can securely encrypt entire volumes using XTS-AES 128 encryption since Lion. Apple calls it File Vault 2.

...and, you can add one more layer of security, setting up a Firmware password. To do so you must boot your computer from Recovery Partition and choose Firmware Password Utility from Utilities menu bar.

If you have a 2010 Mac or later, no one but Apple can unlock, without the correct password, a computer that has Firmware password enabled.

The information I posted would stop a casual person from looking at your files, but as other posters state if you want complete security for your files on any operating system the only way is to encrypt them.

A number of ways have been suggested here, you will need to make your own decision on how far you want to go down that path.

In general the more secure you make your system the more it can impact on its usability, whether from extra CPU usage from decrypting the files as you need them to having to use a password to get the computer to boot up.

If you decide to use a different operations system you will need to make exactly the same decisions that are required with a Mac, the implementation may vary but the principle is the same.

Hope you get the machine as secure as you feel necessary.