Analysis by: Ryan Paolo Maglaque
ALIASES:

Ransom:Win32/Genasom(Microsoft);Mal/MSIL-BA(Sophos)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware, Downloaded from the Internet

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It encrypts files found in specific folders.

  TECHNICAL DETAILS

File Size: 971,776 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 05 Aug 2017
Payload: Displays graphics/image, Encrypts files

Arrival Details

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
payload = {malware file}

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = 1

HKEY_CURRENT_USER\SOFTWARE\Classes\
mscfile\shell\open\
command

Process Termination

This Ransomware terminates the following processes if found running in the affected system's memory:

  • taskmgr

Other Details

This Ransomware does the following:

  • Displays the following lockscreen as ransom note:

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • Desktop
  • CommonProgramFiles
  • CommonProgramFilesX86
  • ProgramFiles
  • ProgramFilesX86
  • CommonDocuments
  • CommonMusic
  • CommonPictures
  • CommonVideos
  • Cookies
  • InternetCache
  • LocalApplicationData
  • Personal
  • MyMusic
  • MyPictures
  • MyVideos
  • StartMenu
  • User Temp
  • {drives that are fixed, removable, and network}

It avoids encrypting files with the following strings in their file name:

  • .kim

It avoids encrypting files found in the following folders:

  • windows

It renames encrypted files using the following names:

  • {Random values}

It appends the following extension to the file name of the encrypted files:

  • .shinigami

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.594.08
FIRST VSAPI PATTERN DATE: 14 Aug 2017
VSAPI OPR PATTERN File: 13.595.00
VSAPI OPR PATTERN Date: 15 Aug 2017

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_CURRENT_USER\SOFTWARE\Classes\mscfile\shell\open\command
    • = {malware file}
  • In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • payload = {malware file}
  • In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
    • DisableTaskMgr = 1

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_SHINIGAMI.A. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 6

Restore encrypted files from backup.


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