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Norton Zone powered by Symantec is a FREE, personal cloud service that lets you safely access and share your photos, videos, and documents from your computer, smartphone, and tablet. Built-in controls let you decide who can access your files and folders, so you can keep your Stuff private when you share.
Quote from https://www.nortonzone.com/
That means Norton knows what you have uploaded. Anyone concerned about the security and privacy of their personal information should not be using this service.
From the multitude of Dropbox security debacles, however, we know that most people don't care about the security of their files.