Immutable Backup Storage for Ransomware Protection

Ransomware often targets backups directly. Attackers know that if they can encrypt or delete your backup files, you have no clean copy to restore from — which makes paying the ransom your only option. Immutable backup storage removes that leverage.

What immutability means:

- Write-once, read-many (WORM) storage prevents backup files from being modified or deleted for a set retention period.

- Even an administrator with full access cannot alter an immutable backup during its retention window.

- Ransomware running under a compromised admin account cannot encrypt or destroy the immutable copy.

Common ways to implement immutable backups:

- Object storage with object lock enabled (for example, S3 Object Lock or Azure Blob immutability policies).

- Tape air-gapped backups, which are physically offline and cannot be reached over the network.

- Dedicated backup appliances with built-in immutability and retention lock features.

Immutable backups work best as part of a layered strategy. Pair them with offline or air-gapped copies, regular test restores, and MFA on backup admin accounts. The goal is simple: if ransomware reaches your primary data, you still have a tamper-proof copy you can trust.