A new version of the MegaCortex Ransomware has been discovered that not only encrypts your files, but now changes the logged in user’s password and threatens to publish the victim’s files if they do not pay the ransom. A new sample of the ransomware was reverse engineered by MalwareHunterTeam and further analyzed by BleepingComputer, we see a new version that has substantial changes from previous variants. The most obvious change seen by victims is the new.m3g4c0rtx extension being used by the ransomware as shown below.
Source: https://www.bleepingcomputer.com/news/security/new-megacortex-ransomware-changes-windows-passwords-threatens-to-publish-data/