Files with the .ZZZ extension contain files that have been securely deleted by computer optimization software. The erased files name and extension are changed to ZZZZZZZZ.ZZZ, which increases security by ensuring that the original name and extension no longer exist.

The software that operates in this way is called CCleaner. The program allows for the optimizing of computers by clearing register logs, deleting unused files and programs, as well as reorganizing the system start procedure.