Ransom.Win32.MEDUSALOCKER.THIBHBC


 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 drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size:

343,552 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

28 Sep 2023

Payload:

Disables AV, Encrypts files, Modifies system registry, Terminates processes

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:

  • To delete backup files:
    • vssadmmin.exe Delete Shadows /All /Quiet
    • wbadmin delete backup -keepVersion:0 -quiet
    • wbadmin DELETE SYSTEMSTATEBACKUP
    • wbadmin DELETE SYSTEMSTABACKUP -deleteOldest
    • wmic.exe SHADOWCOPY /nointeractive
  • bcdedit.exe /set {default} recoverynabled No
  • bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures
  • rem Kill \"SQL\"
  • taskkill -f -m {Target process}
  • net stop {Target service}
  • taskkill /f /im explorer.exe
  • start explorer.exe
  • cipher /w\?\{Drive letter}: → removes deleted files permanently
  • %System%\cmd.exe /c pause
  • {Malware file path} -network

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

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
BabyLockerKZ = {Malware file path}

Other System Modifications

This Ransomware adds the following registry entries:

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

HKEY_CURRENT_USER\Software\PAIDMEMES
PUBLIC = {Ransomware public key}

HKEY_CURRENT_USER\Software\PAIDMEMES
PRIVATE = {Ransomware private key}

Process Termination

This Ransomware terminates the following services if found on the affected system:

  • via net stop:
    • MSSQL$ISARS
    • MSSQL$MSFW
    • SQLAgent$ISARS
    • SQLAgent$MSFW
    • SQLBrowser
    • REportServer$ISARS
    • SQLWriter

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

  • via taskkill /f /im:
    • sqlbrowser.exe
    • sql writer.exe
    • sqlserv.exe
    • msmdsrv.exe
    • MsDtsSrvr.exe
    • sqlceip.exe
    • fdlauncher.exe
    • Ssms.exe
    • SQLAGENT.EXE
    • fdhost.exe
    • ReportingServicesService.exe
    • msftesql.exe
    • pg_ctl.exe
    • postgres.exe

Other Details

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software
PAIDMEMES =

It does the following:

  • Empties Recycle Bin.
  • it encrypts fixed, removable and network drives.
  • It shows its logs within the command prompt:

It accepts the following parameters:

  • -network
  • -shares={Network shares to encrypt} → Encrypts specified network shares
  • -path={Path to encrypt} → Encrypts specified path

Ransomware Routine

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

  • How_to_back_files.html

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

  • \$Recycle.Bin\
  • \Recovery\
  • \System Volume Information\
  • \Windows\
  • \$WinREAgent\
  • \$Windows.~WS\
  • \$WINDOWS.~BT\

It avoids encrypting files found in the following folders:

  • C:\Users\{Username}\AppData\Roaming
  • C:\Users\{Username}\AppData\Local
  • C:\ProgramData
  • C:\perflogs
  • C:\Intel
  • C:\HP
  • C:\AMD
  • C:\Dell
  • C:\Drivers
  • C:\inetpub
  • B:\Boot
  • A:\Boot
  • B:\EFI
  • A:\EFI

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

  • {original filename}.{original extension}.meduza24

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

  • {Encrypted Directory}\How_to_back_files.html

It avoids encrypting files with the following file extensions:

  • .exe
  • .dll
  • .sys
  • .ini
  • .rdp
  • .lnk
  • .bmp
  • .mov
  • .cab
  • .meduza24

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.724.03

FIRST VSAPI PATTERN DATE:

28 Sep 2023

VSAPI OPR PATTERN File:

18.725.00

VSAPI OPR PATTERN Date:

29 Sep 2023

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

     
    • Ransom.Win32.TRX.XXPE50FFF073

Step 2

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 3

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 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\Microsoft\Windows\CurrentVersion\Run
    • BabyLockerKZ = {Malware file path}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
    • EnableLinkedConnections = 1
  • In HKEY_CURRENT_USER\Software\PAIDMEMES
    • PUBLIC = {Ransomware public key}
  • In HKEY_CURRENT_USER\Software\PAIDMEMES
    • PRIVATE = {Ransomware private key}

Step 5

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\PAIDMEMES

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.
  • {Encrypted Directory}\How_to_back_files.html

Step 7

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.MEDUSALOCKER.THIBHBC. 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:

Step 8

Restore encrypted files from backup.


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