A large enterprise uses a centralized backup solution with a backup server running Commvault. Backups are stored on a deduplicated disk array and replicated to a secondary site for disaster recovery. The company's security team detects ransomware activity that has encrypted several file servers. The backup administrator checks the backup repository and finds that the backup data is also encrypted because the backup service account had permissions to modify backup files, and the ransomware propagated to the repository. The last known good backup is from two weeks ago, which is too old for the organization's RPO of 24 hours. The backup administrator is under pressure to restore operations quickly. Which of the following should the administrator implement to prevent this from recurring?