W32/Encoder.A!tr.ransom

Analysis

W32/Encoder.A!tr.ransom is a generic detection for a Ransomware Encoder trojan. Since this is a generic detection, this malware may have varying behaviour.
Below are some of its observed characteristics/behaviours:

• This malware may drop any of the following file(s):
  • !INSTRUCTIONS! : This file is dropped all over the affected hosts drive and will serve as ransom notes.
• Affected files of this Ransomware will use the filenaming format {OriginalFileName.ext}.[epta.mcold@gmail.com].
• This malware was also observed to disable Microsoft Windows Defender system.
• This malware was also observed to delete itself after execution.
• Affected victims of this Ransomware are redirected by the attacker via:
  • epta.mcold@gmail.com
  • epta.mcold@yahoo.com
  • epta.mcold@aol.com
• This malware may apply any of the following registry modification(s):
  • HKCU\Software\Microsoft\Windows\Currentversion\RunOnce
    • WindowsUpdateCheck = %Currentfile%
    This automatically executes the Ransomware every time the infected user logs on.
• Below is an illustration of the malware's ransom notes:

  Figure 1: Ransom note.

Recommended Action

• Make sure that your FortiGate/FortiClient system is using the latest AV database.
• Quarantine/delete files that are detected and replace infected files with clean backup copies.