A new trojan called CryptoLocker is making the rounds which silently encrypts files on your computers, along with files on any connected network storage or USB devices, rendering them unreadable. Once the encryption process finishes, it tells users to pay a ransom, which so far has been $100, $300 or two bitcoins, currently worth about $2400.

Currently, there is no way to recover your data other then from an “offline” backup, if the backup was online or attached at the time of the encryption then more then likely the backup is now encrypted as well.