A new variant of the Power Worm ransomware encrypts your data using AES encryption and then throws away the key. Since the decryption key was not properly encrypted and not saved, a victim’s files become unrecoverable even if they wanted to pay the ransom. The developer planned on using a static AES key for all of his victims. This would allow the developer to have one decryptor that would work for everyone rather than having to manage a intricate payment site and decryption engine. If you are a victim of this infection, DO NOT pay a ransom as it will not help you recover your files.
Source: https://www.bleepingcomputer.com/news/security/shoddy-programming-causes-new-ransomware-to-destroy-your-data/