A method and computer program product with encoded instructions provides for repeatedly making data backups for files by making a series of snapshots of file storage volumes containing the files. The method and computer product further provide for determining that a malware attack has occurred, identifying corrupted files and, for each corrupted file, scanning the series of snapshots to identify an uncorrupted version of the file. Each corrupted file is restored to an uncorrupted version thereof. An event log contains write events and snapshot creation events corresponding to creation of each of the snapshots. A forensic scan scans the event log to determine modifying writes made by the corrupted files and which modified further files. The further files are restored to unmodified versions thereof. A list of at-risk files includes the corrupted files and the further files and the forensic scan is repeated on the at-risk files.