macOS High Sierra Bug Can Give Anyone Root Access to Your Mac - How to Fix

Apple Inc. customers have discovered a significant security flaw in the latest version of the operating system for Mac computers that allows anyone to log in without a password, potentially making private user data vulnerable.

The issue, discovered in the MacOS High Sierra operating system for laptops and desktops that was released in September, allows people to enter the word “root” when prompted for a username, and provide no password when logging on to the device. The glitch allows anyone to access the file system for a Mac, exposing private documents on that particular computer. One user reported the ability to also access the computer using the root login remotely.

The glitch is a rare and potentially embarrassing failure for Apple, whose software is generally known for being less prone to hacking and malware infections than Windows software from Microsoft Corp. The previous version of the operating system didn’t appear to be affected by the bug.

“A password prompt that authenticates as root with an empty password would be a black eye for any OS. Never mind one from a security and privacy-conscious company such as Apple,” Steve Troughton-Smith, a Mac software developer, wrote on Twitter.

Apple spokesman Bill Evans said the company is “working on a software update to address this issue. In the meantime, setting a root password prevents unauthorized access to your Mac.”

Tests of the flaw indicate that it could be used to alter a user’s system settings that normally require a chosen username and password. Some settings include changing key security preferences -- like enabling or disabling a computer’s firewall or storage drive encryption.

The flaw was publicized Tuesday on Twitter by Lemi Orhan Ergin, a software engineer based in Turkey. Edward Snowden, a key voice in the information security community after being the center of many years of National Security Agency leaks, commented on the disclosure. “Imagine a locked door, but if you just keep trying the handle, it says ‘oh well’ and lets you in without a key,” he wrote on Twitter.

Until Apple releases a new version of the software or patches the flaw, users can fix the issue by assigning their own password to the root account. This can be done by navigating to System Preferences, selecting Users and Groups, clicking Login Options on the left side of the menu, clicking the Join button next to Network Account Server, clicking Open Directory Utility, then clicking Edit in the Mac’s menu bar to assign a password. Apple also has instructions available on its website.