What is an Immutable Backup?
An Immutable Backup is a backup that cannot be modified, overwritten or deleted within a predefined period. Even administrators or Ransomware cannot alter its contents.
Immutable = unchangeable. The ultimate protection against data loss.
This technique prevents malicious actors, Malware or human error from sabotaging your backups — a growing threat in light of, for example, Ransomware attacks.
🎯 Examples of Immutable Backups
| Application | Description |
|---|---|
| Object storage (WORM) | Write Once, Read Many — data can be written once and then only read |
| Immutable Cloud Backup | Backup storage in for example AWS S3, Azure Immutable Blob or Wasabi |
| Backup software with immutability | Software such as Veeam, Rubrik or Commvault with write-lock support |
| Air-gapped with immutability | Offline storage combined with write protection (tape, NAS, WORM disks) |
🧯 Why Immutable Backups?
- Protection against Ransomware that tries to encrypt or delete backups
- Prevention of insider sabotage or accidental backup modifications
- Compliance with requirements such as NIS2, ISO 27001 and IEC 62443
- Confidence that recovery points remain reliable and intact
🔁 Immutable vs. traditional backups
| Traditional Backup | Immutable Backup |
|---|---|
| Can be deleted accidentally or maliciously | Cannot be modified or deleted |
| Vulnerable in a Ransomware attack | Untouchable within the retention period |
| Easier to manage, but less secure | Slightly more complex, but far more robust |
🏭 Specifically in OT environments
In OT environments, immutability is crucial for:
- PLC backups that must not be overwritten on a faulty deployment
- SCADA configurations for which you always want a clean copy on hand
- Historical data in Historian systems that is legally or process-critical
- Secure recovery points after sabotage or unauthorised access
📌 In summary
Immutable Backups are the most strongly secured form of data preservation — they are the “airbag” in a digital crash. In an era of Ransomware and supply chain attacks, they are no luxury — they are a necessity.