by Mohit Kumar
November 28, 2017
If you own a Mac computer and run the latest version of Apple’s operating system, macOS High Sierra, then you need to be extra careful with your computer.
A serious, yet stupid vulnerability has been discovered in macOS High Sierra that allows untrusted users to quickly gain unfettered administrative (or root) control on your Mac without any password or security check, potentially leaving your data at risk.
Discovered by developer Lemi Orhan Ergin on Tuesday, the vulnerability only requires anyone with physical access to the target macOS machine to enter “root” into the username field, leave the password blank, and hit the Enter a few times—and Voila!
In simple words, the flaw allows an unauthorized user that gets physical access on a target computer to immediately gain the highest level of access to the computer, known as “root,” without actually typing any password.
Needless to say, this blindingly easy Mac exploit really scary stuff.
This vulnerability is similar to one Apple patched last month, which affected encrypted volumes using APFS wherein the password hint section was showing the actual password of the user in the plain text.
Here’s How to Login as Root User Without a Password
If you own a Mac and want to try this exploit, follow these steps from admin or guest account:
- Open System Preferences on the machine.
- Select Users & Groups.
- Click the lock icon to make changes.
- Enter “root” in the username field of a login window.
- Move the cursor into the Password field and hit enter button there few times, leaving it blank.
With that (after a few tries in some cases) macOS High Sierra logs the unauthorized user in with root privileges, allowing the user to access your Mac as a “superuser” with permission to read and write to system files, including those in other macOS accounts as well.