Sage 50 Server – Ransomware Resilience & Backup Strategy

This document outlines protective layers and backup strategies for your Sage 50 deployment hosted in a Windows Server 2019 VM on Proxmox VE with ZFS storage.

—

✅ Resilience Layer Overview

Layer	Status
ZFS Snapshots	Yes — immutable, instant rollback point-in-time protection
Scheduled Backups	Yes — daily ZFS-based backups (possibly stored locally)
Offline Backups	Not yet — currently no mention of external/offsite isolation
VM Isolation	Yes — Windows Server is isolated in Proxmox VM
Access Model	Yes — RDP with CALs, admin via /admin, Proxmox console for fallback
Firewalling	Possibly — but not yet discussed; no mention of limiting RDP exposure
Restore Time (RTO)	Fast — VM restore or rollback in minutes
Recovery Point (RPO)	1 day — if nightly backups are in place

—

✅ Backup Methods

Method	How-To
External USB SSD (manual)	Plug in once/week, `zfs send` or Proxmox backup job, then unplug
NAS with pull-based rsync	Let NAS pull backups from Proxmox — keeps write access minimal
Cloud backup gateway	Use something like BorgBackup + Rclone for encrypted offsite copy

—

✅ Resilience Impact by Feature

Feature	Resilience Level
On-host ZFS snapshots	High
Immutable off-host backup	Very High
VM isolation via Proxmox	Strong
Hardened access (RDP + VPN)	Very Strong

—

🔐 Hardening Recommendations

Enable Cloudflare Tunnel or VPN for RDP access
Use mstsc /admin for admin, and disable unnecessary RDP users
Set backup destinations to read-only after write
Replicate or export snapshots to a physically separate location
Run regular restore drills to validate RTO/RPO

🧪 Testing Schedule

Task	Frequency
Snapshot rollback test	Monthly
Full VM restore from backup	Quarterly
Air-gapped backup rotation	Weekly (manual)
Security and access review	Bi-annually

Summary

Your Proxmox + ZFS + Windows Server 2019 setup already gives you strong built-in defences. By layering external backups and enforcing hardened access, you achieve full-stack resilience against ransomware.