Since being held ransom in order to regain access to my files I have implemented a deep and comprehensive backup plan. But the fear still haunts me; say I get infected with a virus that can encrypt files on my HD, how am I to plan ahead for this? I'm guessing the answer is include file versioning in my backup plan, which is something I already do. But what if the virus stays dormant until it becomes a part of all file versions (assuming they are time based)?
Backup to read only media such as CDR etc DVD, once written it can't be changed
can back up 25 GB on blue ray single sided
The basic idea is to not give the ransomware easy write access to all backup media.
Create rotating backups on at least two different media that you store disconnect from your machine. That way ransomware can only encrypt at most one backup before you will notice and let it overwrite the other(s).
Backup your files (incrementally) to a network medium, say another machine in the local network or “in the cloud”. I don't think ransomware touches network shares nowadays. If you want to be sure, prevent deletion of old backup data without a password.
Write-protected backup medium
Those will work too, as Steve suggests.