Many of the listed "paranoid" backups suffer from a single point of failure: your computer. If your computer gets compromised then it can silently erase/cryptol

Many of the listed "paranoid" backups suffer from a single point of failure: your computer. If your computer gets compromised then it can silently erase/cryptolock files on your computer or even on your backup drives in the rare event when they are connected. IMO in practice it could only be feasible with a targeted attack after a thorough investigation of your backup plan (assuming if you don't make it public on your blog). I don't know crashplan but AFAIK most backup services suffer from the same problem. If you regularly enter or store account credentials for your backup service then it can be stolen from a compromised computer and can be used to delete backups from the past. It can be mitigated if your backup service provides two accounts for the same backup: an "append only" account and an "administrator" account. The idea that a compromise of the "append only" account can't delete your past backups.