Anyone using MacOS High Sierra should be on high alert. A Twitter user revealed a massive security vulnerability which allows anyone to log into your system as an administrator without valid login credentials. All a malicious user has to do is attempt to log in as “root” from the login screen, leave the password field blank, and press enter over and over until the system allows access.
Dear @AppleSupport, we noticed a *HUGE* security issue at MacOS High Sierra. Anyone can login as "root" with empty password after clicking on login button several times. Are you aware of it @Apple?
— Lemi Orhan Ergin (@lemiorhan) November 28, 2017
The scary news is that it’s true, or it was before Apple released a security patch. So all you need to do is open your Mac App Store and check for updates. You should see a security update available, go ahead and download that and you’re all set. Before it was fixed, the vulnerability meant anyone could approach your iMac, MacBook, or Mac Pro and access your computer without anything more than a couple keystrokes and zero technical know-how.
Additionally, it’s never a bad idea to change your system’s root password; leaving it blank was the key to the vulnerability before it was fixed. Here’s a quick tutorial on how to do just that.
Assuming you’re running MacOS High Sierra, we’ll teach you below how to fix the problem.
First, we’re going to open up System Preferences, open Users & Groups, select Login Options, then click the lock on the bottom left side of the window and enter your password. Next, hit Join right beside Network Account Server. This will open up a small dialog box, there you will want to click Open Directory Utility. Now we’re going to click that little lock again, and enter your password.
From here, mouse up to your Finder bar, and click Edit. From this drop-down menu click Change Root Password. This is the most important part: Pick a strong, unique password that you won’t forget.
That’s it, just an extra layer of security for your Mac, now that Apple has addressed the vulnerability with a security update.
The whole issue came to light after an industrious Twitter user pinged Apple Support’s official Twitter account for help regarding the vulnerability and from there it caught fire and spread. Twitter users from all over the world were confirming that they could replicate the vulnerability, and access their own computers without using anything more than a four-letter word.
Even though it’s fixed, this wasn’t just a minor vulnerability, like a loophole in some bit of code somewhere that only a security expert could exploit. This was a dead-simple way to break into someone else’s computer, so make sure you download and apply that patch from the Mac App Store.
Update: Apple has issued a security patch to address the issue.