The best thing I can suggest is regular, invisible backups. Ensure that it's very difficult for them to avoid doing the backups, and make sure that what ever ho

The best thing I can suggest is regular, invisible backups. Ensure that it's very difficult for them to avoid doing the backups, and make sure that what ever holds the backups is a battle-hardened. Social engineering is a broad problem right now, and all you can really do is be prepared to pick up the pieces after the fact.