Aqui está um script do Powershell que fará o trabalho ...
Open the RDG file with notepad to get the encrypted password. I found that RDG contained the 'profiles' I had saved, as well as the passwords saved per server.
Now use the same computer and windows account that created the RDG file to run the following powershell commands to see the password. You have to use the same account to decrypt.
$PwdString = 'EnCryptEdStringFRoMRDGfile=='; Copy-Item 'C:\Program Files (x86)\Microsoft\Remote Desktop Connection Manager\RDCMan.exe' 'C:\temp\RDCMan.dll' Import-Module 'C:\temp\RDCMan.dll' $EncryptionSettings = New-Object -TypeName RdcMan.EncryptionSettings [RdcMan.Encryption]::DecryptString($PwdString, $EncryptionSettings)
Fonte: link por THOMAS PRUD'HOMME