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Comment by jcoby | Hacker News Reader

Be careful testing this! It appears that you're creating a "root" superuser with no password. Be sure to clean up that user afterwords.

https://twitter.com/a_hailes/status/935601901839806464

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It's worse than that. You're enabling the root user EVERY time you use this vulnerability. Even if you disable the root user in Directory Utility, logging in with root and no password will re-enable the root user.

I haven't upgraded to High Sierra yet and this doesn't happen on my install atm. Does adding a password to the root user stop this vulnerability? If it does then that seems way better than disabling the account until this is fixed.

You can simply set a root password with "sudo passwd" to close the hole.

Then you better remember the password you set, or be sure that you will always have sudo access.

And you might want to disable the root account again with `dsenableroot -d` as well, so that the root account stays disabled after the vulnerability is patched.

Unlike doing this through the GUI, this seems to retain the root password and prevent this vuln from re-occuring.

Don't disable root. The bug re-enables it with a new blank password.

It doesn't if you disable it from the shell like this, as I note in my comment.

I've tested both approaches - disabling via the GUI causes this bug to re-occur next time you try, disabling via the shell does not.

Bizarrely though, you can still use the root user (with the password that you set) to login to the Directory Utility even while it is supposed to be disabled... This behaviour seems super weird.

Yeah I've noticed this myself - I'm on the fence as to whether this is actually disabling the account or simply creating that impression (it does show as disabled in Directory Utility after you perform this command).

My hope in recommending people disable this way is that with the additional scrutiny on this subsystem, accounts disabled this way will remain genuinely disabled in a future update. Either way this doesn't seem to reintroduce the bug.

... but the whole thing is a mess overall.

I confirm, disabling from shell does seem to prevent further logins

As far as I can tell, "dsenableroot -d" seems to have no useful effect. After having "* Successfully disabled root user." with it, I can still log in to the root account with the password I set, both at the command line with "login" and from a remote machine via screen sharing.

To be flippant, I might say HN discussions seem to QA using Apple methods.

...unless you set a password, right?

You're not creating it, but rather enabling it. When the bug is triggered, the root user is enabled (per Directory Utility).

But you are creating the password for it.

This support article explains how to disable the root user: https://support.apple.com/en-us/HT204012

Do note that this doesn't fix the problem. The system (at least High Sierra) will happily re-enable the user for every attempt at logging in.

Just change the root password once the account is enabled; this fixes the hole.

sudo passwd -u root

It's sad we have to do this, though.

If you disable the root user using `dsenableroot -d` from the Terminal, this seems to disable the account in a way that leaves its password intact.

The bug isn't in the disabling, it's in the auto-enabling on attempt.

Having tested this by both approaches (disabling through GUI & shell), the above (through shell) seems to prevent this from re-occurring when you attempt to perform this bogus login again. Disabling the account via the GUI causes the failure to re-occur.

Until this is fixed it's probably better to use Directory Utility to enable root with a strong password.

/System/Library/CoreServices/Applications/Directory Utility.app

Edit > Change Root Password

The "root" superuser is always there, I'm not sure if it's possible to actually delete it.

It is disabled by default[1] (meaning you can't login as it), this vulnerability appears to enable the root user without setting a password. If the root user has already been enabled it doesn't work.

Anyone who does this should probably set a password for now and then disable the root user account once it has been patched.

[1] https://support.apple.com/en-us/HT204012

This is the best workaround for now. Enable the root user with a strong password till the bug is fixed by Apple.

oh my god

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