Ransomware attackers specifically target and attempt to destroy backup systems to increase the probability of payment. Hardening your system is critical. Please ensure you have reviewed your platform security using the Security Hardening Checklist
Best practices for key file restoration — NetBackup 11.1.0.2 | Cohesity Documentation
Best practices for key file restoration
Even when an encrypted backup does not have a key file available, you may be able to restore the files.