What is Recovery?

Recovery only starts once eradication is confirmed complete; restoring a system while a backdoor or scheduled task still exists just hands the attacker back their access on a freshly rebuilt host. The core work is rebuilding trust in the environment: restoring from backups or clean images, validating integrity (checksums, known-good baselines, application functional testing) before the system touches production traffic, and bringing connectivity back in a controlled sequence rather than flipping every switch at once. A common pattern after a ransomware incident is restoring the domain controllers and core identity infrastructure first, verifying no persistence remains, then bringing back file servers, then application tiers, each stage watched for anomalous activity before the next stage proceeds.

Backup integrity deserves specific scrutiny because ransomware operators increasingly target backup infrastructure directly, deleting shadow copies, encrypting backup repositories, or sitting dormant in the environment long enough that daily backups also capture the compromise. Before restoring from backup, teams verify the backup predates the attacker's initial access, not just the point of encryption, and scan the restored data for malware before it goes live. Immutable, offline, or air-gapped backups that an attacker with domain admin cannot reach or modify are the control that makes recovery reliable rather than aspirational.

Recovery closes with the lessons-learned review: what detection gap allowed the incident to progress as far as it did, what response step took longer than it should have, and what changes (new detection rules, revised playbooks, additional log sources) prevent a repeat. NIST CSF's Recover function (RC.RP for recovery planning, RC.IM for improvements, RC.CO for communications) maps directly onto this phase, and mature organizations treat the lessons-learned output as mandatory input to next quarter's detection engineering backlog, not a document that gets filed and forgotten.

Recovery timing also carries regulatory and communication obligations that run in parallel with the technical work. If the incident involved personal data, breach notification clocks (72 hours under GDPR, shorter windows under some US state laws) may already be running before systems are even back online, so legal and communications teams coordinate with the technical recovery timeline rather than waiting for it to finish. Customer-facing or partner-facing status updates during recovery need to be accurate about what's restored and what's still being validated, since overstating readiness and then suffering a second outage or a second compromise does more reputational damage than an honest, phased status report.