MSIL/Boom.1FD2!tr.ransom

Analysis

MSIL/Boom.1FD2!tr.ransom is a generic detection for a Ransomware Boom 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):
  
  • %Temp%svchost.exe : This file is currently detected as W32/Boom.1FD2!tr.ransom .
  • %Temp%\bdx48saerp3j6l1.exe : This file is currently detected as W32/Boom.1FD2!tr.ransom.
  • how to decrypt files.txt : This text file will serve as ransom note. It is dropped in every infected folder.


• This Ransomware attempts to stop the explorer.exe process from running.


• Affected files of this Ransomware will use the filenaming format {Originalfilename.Ext}.Boom


• This malware was also observed to affect/encrypt files located on shared drive within the same subnet.


• This malware may apply any of the following registry modification(s):
  
  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Currentversion\Run
    
    • Alcmeter = %Temp%\bdx48saerp3j6l1.exe
    The malware configures itself to run everytime any user logs on to the infected system.
    
  • HKEY_LOCAL_MACHINE\Software\Wow6432node\Microsoft\Windows\Currentversion\Run
    
    • Alcmeter = %Temp%\bdx48saerp3j6l1.exe
    The malware configures itself to run everytime any user logs on to the infected system.
    


• Below is an illustration of the malware's Ransom notes:
  

  Figure 1: Ransom note .

  
  

  Figure 2: Message prompt .

  
  

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.