This is a highly theoretical and experimental mitigation which stops the root password on newly upgraded/installed systems from being an empty string. The thinking is that by not shipping an operating system with a known root password, certain classes of attacks involving logging into the root account might be avoided. I would like some feedback from the cryptography team as well as NIST finalists in order to better ascertain the implications of this behaviour.
Index: src/distrib/miniroot/install.sub =================================================================== RCS file: /cvs/src/distrib/miniroot/install.sub,v retrieving revision 1.1032 diff -u -p -r1.1032 install.sub --- src/distrib/miniroot/install.sub 8 Aug 2017 07:14:05 -0000 1.1032 +++ src/distrib/miniroot/install.sub 28 Nov 2017 23:43:56 -0000 @@ -2732,12 +2732,6 @@ do_install() { echo + while :; do + ask_password "Password for root account?" + _rootpass="$_password" + [[ -n "$_password" ]] && break + echo "The root password must be set." + done # Ask for the root user public ssh key during autoinstall. _rootkey=