A vulnerability was discovered in macOS High Sierra (10.13, 10.13.1, 10.13.2 beta) today that allows an attacker to gain root access to your system if your root account is disabled and has no password set (which is the default). If you are running High Sierra, please mitigate this attack by enabling your root account and setting a strong password for it.
https://support.apple.com/en-us/HT204012 https://www.macrumors.com/2017/11/28/macos-high-sierra-bug-admin-access/