The Mailto / Netwalker Ransomware is targeting enterprise networks. The Australian Toll Group disclosed that their network was attacked by the Mailto ransomware. Analysis of one of its decryptors indicates that it is named Netwalker. The malware is still being analyzed and it is not known if there are any weaknesses in the encryption algorithm that can be used to decrypt files. For example, in our test run the ransom note was named 77D8B-Readme.txt. The ransom note will contain information on what happened to the computer and two email addresses.
Source: https://www.bleepingcomputer.com/news/security/mailto-netwalker-ransomware-targets-enterprise-networks/