A security researcher analyzed a new ransomware called NanoLocker. He found that it contains some interesting features including how it communicates with the Command & Control server and a flaw in the way it temporarily stores the key. This flaw can the be used to decrypt a victim’s files in the right circumstances. The program is now running silently in the background and scanning your drives for data to encrypt. When it finds a targeted data file it will encrypt it using AES encryption and then an add the file and its path to the %LocalAppData%lansrvini file.
Source: https://www.bleepingcomputer.com/news/security/nanolocker-ransomware-can-be-decrypted-if-caught-early/