Security experts at Bitdefender speculate that the newborn Cryptowall 4.0 has a Russian origin. The malware researchers also confirmed that encryption algorithm used to encrypt the victims files is the unbreakable AES 256 and the key is encrypted using RSA 2048. The company released a vaccine software that allows users to immunize their computers and block file encryption process implemented by ransomware, including the CryptoWall. The criminals behind the dreaded ransomware already made $325 million from the sale of CryptoWall 3.0.”]
Source: https://securityaffairs.co/wordpress/41862/cyber-crime/cryptowall-4-0-russia-vaccine.html