With High Sierra causing so many issues for Enterprise environments at the moment you may want to block the install. This can be achieved in various ways.

If you are using Jamf MDM then a simple Restricted Software policy can stop the install:

However this won’t stop macOS downloading the updater in the background and prompting the user to install, but there are two other commands we can issues to try and stop auto updates and notifications:

To stop Auto Updates:
defaults write /Library/Preferences/com.apple.SoftwareUpdate AutomaticCheckEnabled -bool FALSE


To turn Auto Updates back on:
defaults write /Library/Preferences/com.apple.SoftwareUpdate AutomaticCheckEnabled -bool TRUE


To turn off High Sierra notifications
sudo softwareupdate --ignore macOS High


An when you do want to allow notifications you can switch it back on with:
sudo softwareupdate --reset-ignored