Bear in mind when you are setting up your backup strategy that crypto-ransomware like CryptoLocker will also encrypt files on drives that are mapped, and some modern variants will look for unmapped drives too. Crypto-ransomware will look for external drives such as USB thumb drives, as well as any network or cloud file stores that you have assigned a drive letter to.
You need to set up a regular backup regimen that at a minimum backs up data to an external drive, or backup service, that is completely disconnected when it is not performing the backup.
The recommended best practice is that your data and systems are backed up in at least three different places.
- Your main storage area (file server)
- Local disk backup
- Mirrors in a cloud business continuity service
In the event of a ransomware disaster, this set-up will give you the ability to mitigate any takeover of your data and almost immediately regain the full functionality of your critical IT systems.