Full Disk Access is a new security feature in macOS Mojave that requires some applications to be given full permission to access a user's protected files. In previous versions of macOS, this permission was automatically given to all applications at the time of installation. If a user chooses not to give Full Disk Access, some data on the Mac will not be accessible.
macOS Mojave (10.14) introduced certain privacy protections that, by default, block applications’ access to specific system application folders and resources, such as Mail, Messages, Safari, Home and Time Machine backups. For Trend Micro Antivirus for Mac to scan and protect those protected locations, user must allow Full Disk Access to the iCoreService file, an important component of Trend Micro Antivirus for Mac.