If you want to get the root password hash into memory, just run sudo, or any other root process that reads /etc/shadow. It'll probably get it mapped into the fi

If you want to get the root password hash into memory, just run sudo, or any other root process that reads /etc/shadow. It'll probably get it mapped into the file system cache, but it'll certainly get it mapped into that process's memory - albeit potentially temporarily. I don't know that sudo takes any measures to protect that memory. You say "lots of modern software" but it's more like "the extreme minority of software" with regards to security effort.