Immutable backup
A backup that cannot be modified or deleted for a defined period, even by an administrator.
Ransomware crews delete or encrypt backups before triggering the main event, and they do it using stolen administrative credentials, so ordinary permissions do not stop them. Immutability is enforced by the storage platform and ignores those credentials entirely.
This has become the control that separates a recoverable incident from a rebuild, and insurers now ask about it directly on applications.
Where this comes up
Immutable backup sits inside our backup and disaster recovery work. If you are trying to work out what this means for your own environment rather than in the abstract, that is the page worth reading next, and a short call will get you a straight answer faster than either.