Immutable Backup

Overview

An immutable backup is a backup copy that cannot be altered or deleted during a defined retention period, including by ordinary administrators or compromised production credentials.

Immutable Backup is closely connected to ICT Response and Recovery Plan, Recovery Control, and Post-Incident Review. It differs from an offline backup because immutability describes resistance to modification, while offline or air-gapped storage describes connectivity; a resilient design may use both properties.

Operational implementation should separate backup identities, enforce write-once retention, isolate management paths, encrypt copies, test restoration, monitor deletion attempts, maintain multiple generations, and protect keys and catalogs.

The principal failure modes include misconfigured retention, shared credentials, untested restores, corrupted source data, compromised backup software, expired copies, and backups that omit critical dependencies.

Useful measures include successful restore rate, immutable-copy coverage, backup age, deletion attempts, recovery time, and percentage of critical services with tested copies.

Operationally, teams should separate backup identities, enforce write-once retention, isolate management paths, and encrypt copies. Key risks include misconfigured retention, shared credentials, untested restores, and corrupted source data.

A production treatment of Immutable Backup should test a backup copy that cannot be altered or deleted during a defined retention period, including by ordinary administrators or compromised production credentials within the relevant asset, decision, or service state. The Immutable Backup context record for backup copy that cannot be altered, deleted during a defined retention period, and including by ordinary administrators should preserve source data, configuration or policy version, responsible actor, exception, and outcome. Review of Immutable Backup should determine whether safeguards addressing backup copy that cannot be altered, deleted during a defined retention period, and including by ordinary administrators changed exposure in practice, not merely whether a document or setting existed.