I do both: I backup to my Synology NAS, which then in-turn uses Synology's Hyper-Backup (which is very nice, btw) to my Azure storage account - costs me about $15/mo to store a few terabytes with PITR recovery back to when I started doing this in 2018.
The thing is... I can't help but worry someone's going to compromise my NAS and DBAN the drives and then extract the Azure storage key and use that to delete all my backup blobs...
(Yes, the backup client needs read, write, and delete permissions, unfortunately - and Azure doesn't offer a Blockchain-style "append-only" mode for blob storage, unfortunately - still, better than nothing).
UPDATE: Apparently Azure Blob Storage does support strict append-only blobs that cannot be mutated or deleted, only appended - so I wonder if Hyper-Backup can use that…
Is there anyone out there with $$$$ who will stop at nothing to part you, a rando, from your old data? Probably not. Are there sophisticated attackers who will burn a couple 0-days to build a botnet for the sole purpose of randsoming NASes AND attached cloud accounts AND the origin systems, accounting for tons of possible configurations? Still pretty unlikely — this is NotPetya level stuff with small payoff.
If you find yourself in the crosshairs of a sophisticated, dedicated attacker (perhaps one in possession of a 0-day), you’re pretty much done. Offline write-only backups stored offsite are the only defense.
However, is there a bug lurking in Hyper-backup that might accidentally wipe stuff from Azure storage, and the bug hits a month before your house gets struck by lightning? Maybe…
> However, is there a bug lurking in Hyper-backup that might accidentally wipe stuff from Azure storage, and the bug hits a month before your house gets struck by lightning? Maybe…
The thing is... I can't help but worry someone's going to compromise my NAS and DBAN the drives and then extract the Azure storage key and use that to delete all my backup blobs...
(Yes, the backup client needs read, write, and delete permissions, unfortunately - and Azure doesn't offer a Blockchain-style "append-only" mode for blob storage, unfortunately - still, better than nothing).
UPDATE: Apparently Azure Blob Storage does support strict append-only blobs that cannot be mutated or deleted, only appended - so I wonder if Hyper-Backup can use that…