Root Me Baby One More Time!

UPDATE: Apple has posted a security update. 2017-001

Root-a-pocalyse. Root down. Root a toot toot. Many funny tweets today about a very serious issue. A bug was discovered in macOS 10.13 that enabled anyone to login with a root account. With no password. Wow. Seriously. Yeah, that’s bad.

Bug discovered by Lemi Orhan Ergin.

I tested by clicking on the lock icon in System Preferences. Normally this requires an admin account. I was able to authenticate with “root” and no password. This actually also set root to no password. You can choose a password here and this makes it for you. How convenient. You can also login to the Mac via the login window. With root. And no password. Crazy.

If your Mac is off it’s safe. Not joking. If your FileVault protected drive is encrypted and your mac is turned off then you’re good. If you Mac is turned on and you’ve logged in at least once (or at least decrypted the drive on boot) then you’re not safe.

What can you do? Change the root password and set the shell to false. Until Apple fixes this. Should be anytime now. Or soon.

dscl . -passwd /Users/root “random or very secure password here”

dscl . -create /Users/root UserShell /usr/bin/false

Read a comprehensive explanation on Rich Trouton’s site:  Der Flounder blog

 

Setting up Secure Munki

So you’ve set up Munki to deploy software to your Macs by following the basic set up here: Set up Munki, and now you want to set it up more securely.

You need two things. 1) a cert and 2) a secure repo

  • TRUST US

The optimal situation is a trusted secure certificate for your server from a reputable certificate authority, if you don’t have that, or want to use the self-signed certificate your server has then your Munki Mac clients will need to trust this certificate.

Export out the cert from Server Admin if you’re using that to manage your Mac mini server. Place this cert file on your clients (using ARD, or other methods) then use the security command to get the Mac clients to trust this cert.

security add-trusted-cert -d -r trustRoot -k “/Library/Keychains/System.keychain” “/private/tmp/name-of-server.cer”

REFERENCE: Rich Trouton’s blog goes into more detail and details a way to script this.

  •  SECURE IT

Use htpasswd to add a password to your Munki repo.

htpasswd -c .htpasswd munki

Edit the htaccess info

AuthType Basic
AuthName "Munki Repository"
AuthUserFile /path/to/your/munki/repo_root/.htpasswd
Require valid-user

Encode this password for Munki:

python -c 'import base64; print "Authorization: Basic %s" % base64.b64encode("USERNAME:PASSWORD")'
Authorization: Basic VVNFUk5BTUU6UEFTU1dPUkQ=

Push out this password to your Munki clients with ARD (or use some other method)

defaults write /Library/Preferences/ManagedInstalls.plist AdditionalHttpHeaders -array “Authorization: VVNFUk5BTUU6UEFTU1dPUkQ=”

Change the Munki RepoURL on all your clients to use the new secure URL

defaults write /Library/Preferences/ManagedInstalls SoftwareRepoURL “https://munkiserver/munki_repo”

REFERENCES:

Consult the Munki Wiki for: Basic authentication setup for Munki 

Ala Siu’s excellent write on securing munki

Notes:

Consider using a server made for securing Munki, like the Squirrel server from the MicroMDM project. More on this in another blog post.

Consider using certificate from a known reputable certificate authority such as Let’s Encrypt (the Squirrel server above automates the setup with Let’s Encrypt).

Further:

Another project which seeks to combine all these open source projects in the Munki ecosystem is Munki in a Box. There’s a secure branch of this project which setups a basic authentication as well but while it aims to simplify setting up a secure Munki it may be a bit confusing to set up at first glance. Test, and test again.