MSIL/HiddenTear.DAA6!tr.ransom

Analysis

MSIL/HiddenTear.DAA6!tr.ransom is a generic detection for a Ransomware HiddenTear 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):
  • %systemdrive%\files\1.exe : This file is detected as MSIL/Filecoder.Y!tr.
  • %appdata%\img.jpg : This file is an image and will serve as ransom notes.
• This malware may apply any of the following registry modification(s):
  • HKCU\ControlPanel\Desktop\Wallpaper
    • img.jpg = %appdata%\img.jpg
    This sets the desktop wallpaper with a ransom note.
• Below is an illustration of the malware's Ransom notes:

  Figure 1: Ransom note.

  Figure 2: 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.