Credentials stored in VisualCron are obviously stored in backups. Backups can be restored in any VisualCron instance, so if you have a copy of the backup you can essentially use any of the credentials stored in this instance. The task automation features make it likely that you can exploit this in a very easy manner.

Backups are already zipped, so would it perhaps be possible to add encryption to zip files and/or backups in VisualCron to perhaps mitigate this risk? By default WinZip offers various types of encryption, varying in strength:
http://kb.winzip.com/kb/entry/80/ 
For the backups in particular they it needs to be possible to restrict who can access the password field.