Attachment security/accessibility

Hi, can you provide some info as to if attachments in syncro customer/tickets/devices etc are publicly accessible to anyone with the link?

We’ve uploaded a spreadsheet containing a list of contact details. When clicking on the link within syncro, we’ve then copied this to another machine and the link opens without needing to be logged into Syncro. This obviously will change what we consider safe to attach to Syncro, please advise