A major new macOS vulnerability has just been discovered, and it’s also been disclosed publicly…on Twitter. The bug gives anyone unauthorized administration access to a Mac using a very simple trick: logging in as root.

When trying to login to a macOS device running High Sierra, you will simply need to use the username “root”, leave the password field empty, and then hit the login button a couple of times to get access to the device. The vulnerability affects all latest versions of the operating system, but it only seems to affect devices running macOS High Sierra and can’t be reproduced on older versions of the OS.

Using the same trick, you can add new users (even as admins) to a device, remove other users, reset their passwords, decrypt disks encrypted by FileVault, or change almost every other setting that requires admin access. It’s pretty ridiculous:

Apple has yet to acknowledge the security flaw on macOS, but the only way of getting around the issue actually requires you to enable a root user on your device, as you will be asked to set a password for the root user that can’t be bypassed using the trick mentioned above. Disabling the root user won’t help, by the way. The security flaw isn’t too much of a big deal, though, as one would need physical access to your device in order to get unauthorized administrative access to your device.

Still, flaws like this really undermine the level of security you get from Apple’s premium devices, even though such issues are rarely discovered.

Tagged with macOS, macOS High Sierra, Security