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Ransom_SCARAB.G

August 31, 2018
 Analysis by: Robert Nicole Malagad
 ALIASES:

Ransom:Win32/Kitoles.A (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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 is capable of encrypting files in the affected system.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

214,528 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

19 Aug 2018

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.

Installation

This Ransomware drops the following copies of itself into the affected system:

  • %Application Data%\osk.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

It adds the following processes:

  • "C:\Windows\system32\cmd.exe" /c copy /y "C:\Users\dyituser_732\Downloads\{Malware File Name}.exe" "%Application Data%\osk.exe";
  • mshta.exe "javascript:o=new ActiveXObject('Scripting.FileSystemObject');setInterval(function(){try{o.DeleteFile('{Malware File Name}.exe');close()}catch(e){}},10);"
  • mshta.exe "javascript:o=new ActiveXObject('WScript.Shell');x=new ActiveXObject('Scripting.FileSystemObject');setInterval(function(){try{i=x.GetFile('osk.exe').Path;o.RegWrite('HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce\{Random Name}',i);}catch(e){}},10);"
  • mshta.exe "javascript:eval(new ActiveXObject('WScript.Shell').RegRead('HKCU\Software\{Random Name}\E[XTS'));close();"
  • "C:\Windows\System32\cmd.exe" /c wbadmin DELETE SYSTEMSTATEBACKUP -keepVersions:0
  • "C:\Windows\System32\cmd.exe" /c wmic SHADOWCOPY DELETE
  • "C:\Windows\System32\cmd.exe" /c vssadmin Delete Shadows /All /Quiet
  • "C:\Windows\System32\cmd.exe" /c bcdedit /set {default} recoveryenabled No
  • "C:\Windows\System32\cmd.exe" /c bcdedit /set {default} bootstatuspolicy ignoreallfailures
  • wbadmin DELETE SYSTEMSTATEBACKUP -keepVersions:0
  • C:\Windows\System32\cmd.exe;new process;vssadmin Delete Shadows /All /Quiet
  • C:\Windows\System32\cmd.exe;new process;wmic SHADOWCOPY DELETE
  • C:\Windows\System32\cmd.exe;new process;bcdedit /set {default} recoveryenabled No
  • C:\Windows\System32\cmd.exe;new process;bcdedit /set {default} bootstatuspolicy ignoreallfailures

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

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\RunOnce
TScZfk = %Application Data%\osk.exe

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\{Random Letters}

HKEY_CURRENT_USER\Software\TScZfk

Other Details

This Ransomware is capable of encrypting files in the affected system.

Ransomware Routine

This Ransomware renames encrypted files using the following names:

  • {Location of Encrypted File}\{Encrypted Filename}.amnesia

It drops the following file(s) as ransom note:

  • {Location of Encrypted File}\??? ???????????? ?? ?? ?????? ?????.TXT

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.144.03

FIRST VSAPI PATTERN DATE:

22 Mar 2018

VSAPI OPR PATTERN File:

14.145.00

VSAPI OPR PATTERN Date:

23 Mar 2018

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 key

[ 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
    • TScZfk
  • In HKEY_CURRENT_USER\Software
    • {Random Letters}

Step 5

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\Microsoft\Windows\CurrentVersion\RunOnce
    • TScZfk = %Application Data%\osk.exe

Step 6

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • {Location of encrypted file}\??? ???????????? ?? ?? ?????? ?????.TXT

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom_SCARAB.G. 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 8

Restore encrypted files from backup.

NOTES:
Enable Windows Recovery Option:

  • Run cmd.exe as administrator.
  • Type bcdedit /set {default} recoveryenabled yes then press Enter.


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