Which of the following should the IT administrator do FIRST after recovery?

A small business just recovered from a ransomware attack against its file servers by purchasing the decryption keys from the attackers. The issue was triggered by a phishing email and the IT administrator wants to ensure it does not happen again.

Which of the following should the IT administrator do FIRST after recovery?
A . Scan the NAS for residual or dormant malware and take new daily backups that are tested on a frequent basis
B . Restrict administrative privileges and patch ail systems and applications.
C . Rebuild all workstations and install new antivirus software
D . Implement application whitelisting and perform user application hardening

Answer: A