It seems like attachments that are uploaded are not very secure (because when the document is uploaded to the web, anyone who knows the URL can access and download the document). I understand that there is some security around the idea that it is unlikely someone could guess the correct URL, but it still worries me enough to not want to upload anything sensitive as an attachment. I would like it if the URL does not work unless a user who is authorized to collaborate on a specified Base is logged in on their browser.