Yup, I'll chip in with advice:
Ask the client to hunt and see if he has any backups from before he got hit with a ransomware attack, because that file is not attachable. I suspect it too is encrypted and hence unreadable.
Or pay the ransom and hope he gets the key.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability