The best way to ensure the capability to restore clean data after a ransomware attack is to maintain multiple offline backups. Offline backups are backups that are not connected to the network or the internet, and therefore are not accessible by ransomware. Multiple offline backups provide redundancy and allow the organization to choose the most recent and uncorrupted backup to restore the data. Offline backups should be stored in a secure location and tested regularly to ensure their integrity and availability.
Purchasing cyber insurance may help the organization cover some of the costs associated with a ransomware attack, such as ransom payment, data recovery, legal fees, etc., but it does not guarantee the capability to restore clean data. Cyber insurance policies may have exclusions, limitations, or conditions that affect the coverage and reimbursement. Moreover, cyber insurance does not prevent or mitigate the ransomware attack itself, and it may not cover all the losses or damages caused by the attack.
Encrypting sensitive production data may protect the confidentiality of the data from unauthorized access or disclosure, but it does not prevent ransomware from encrypting the data again. Ransomware does not need to decrypt the data to encrypt it, and it may use a different encryption algorithm or key than the one used by the organization. Encrypting production data may also increase the complexity and time required for data recovery, especially if the encryption keys are lost or compromised.
Performing integrity checks on backups may help the organization verify that the backups are not corrupted or tampered with, but it does not ensure the capability to restore clean data after a ransomware attack. Integrity checks are a preventive measure that should be done before the attack, not after. If the backups are already infected or encrypted by ransomware, performing integrity checks will not help to recover the data. Integrity checks should be complemented by other measures, such as isolation, versioning, and offline storage, to protect the backups from ransomware. References = CISM Certified Information Security Manager Study Guide, Chapter 9: Business Continuity and Disaster Recovery, page 3081; CISM Foundations: Module 4 Course, Part Two: Business Continuity and Disaster Recovery Plans2; Ransomware recovery: 8 steps to successfully restore from backup3; Ransomware Recovery: 5 Steps to Recover Data4
