There is only one file type that uses the .LIVEUPDATE extension:
Symantec LiveUpdate File
File used by LiveUpdate, a program used to update Symantec antivirus programs; contains data for updating antivirus software and virus definitions; facilitates remote software updates by providing local computer and software information.
Common LIVEUPDATE files include Settings.LiveUpdate, Log.LiveUpdate, and Product.Inventory.LiveUpdate.
Updated: July 10, 2012