Database backup restore disaster

Unfortunately a customer of mine is having a hard time as they were infected with ransomware.
The SQL Server database backups however were stored elsewhere but I am unable to restore it it seems.

When trying to use the GUI to restore the database, it tries to read the header information and fails with this error:

The backup data at the end of "C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\Backup\TheBackup.bak" is incorrectly formatted. Backup sets on the media might be damaged and unusable. To determine the backup sets on the media, use RESTORE HEADERONLY. To determine the usability of the backup sets, run RESTORE VERIFYONLY. If all of the backup sets are incomplete, reformat the media using BACKUP WITH FORMAT, which destroys all the backup sets.

And then in the event log:

BackupIoRequest::ReportIoError: read failure on backup device 'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\Backup\TheBackup.bak'. Operating system error 13(The data is invalid.).

I am not sure what else to do, how to restore the data. Any ideas? I know it maybe far fetched but anything is much appreciated and welcomed, even if it is going through a fine comb/row by row - whatever.

Doing a restore filelist shows me 2 entries (the MDF and LDF) but when I try to do this:

FROM DISK = N'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\Backup\TheBackup.bak'
MOVE N'DB_Data' TO N'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\Backup\TheBackup.mdf',
MOVE N'DB_log' TO N'C:\Program Files\Microsoft SQL Server\MSSQL12.MSSQLSERVER\MSSQL\Backup\TheBackup_log.ldf',

Still results in the error.


What is the result from RESTORE HEADERONLY and RESTORE VERIFYONLY? Run these commands in a query window instead of through the GUI so you can see the full results.

Is it possible that these are striped backups - or backups taken with a different utility?