Microsoft security software detects and removes this threat.
This ransomware encrypts the files on your PC and directs you to a webpage with instructions on how to unlock them. It can ask you to make a payment using bitcoins.
The ransom or "lock" screen can use the name CryptoDefense or CryptoWall.
See the Win32/Crotwi family description for more information.
You can also read more about this type of threat on our ransomware page.