Spora ransomware has joined the family of ransomware created by professionals. Some of the elements suggest that there is a well-prepared team of criminals behind it. The malware runs silently and encrypts files with selected extensions. Each file is encrypted with a separate key (ones with the same plaintext are encrypted to different ciphertexts). Encrypted content has high entropy, no patterns are visible, that suggest a stream cipher or chained blocks (probably AES in CBC mode) When the encryption finishes, a ransom note pops up.”]
Source: https://blog.malwarebytes.com/threat-analysis/2017/03/spora-ransomware/