Analysis by: Francesca Villasanta

ALIASES:

Trojan:Win32/Leonem (MICROSOFT); Win32/Filecoder.Lockbit.M trojan (NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

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

  TECHNICAL DETAILS

File Size: 1,137,671 bytes
File Type: PS1, DLL
Memory Resident: No
Initial Samples Received Date: 30 Apr 2023
Payload: Modifies system registry, Displays message/message boxes, Drops files, 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.

Installation

This Ransomware drops the following files:

  • %Program Data%\{4 random characters}.tmp
  • %Program Data%\Ck8GvVQ9E.ico
  • %System Root%\{8 random characters}\{random}.tmp → deleted afterwards

It adds the following processes:

  • %Program Data%\{4 random characters}.tmp

It creates the following folders:

  • %System Root%\{8 random characters}

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

Other System Modifications

This Ransomware adds the following registry entries as part of its installation routine:

HKEY_LOCALMACHINE\SOFTWARE\Classes\
Ck8GvVQ9E\DefaultIcon
(Default) = %ProgramData%Ck8GvVQ9E.ico

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.Ck8GvVQ9E
(Default) = Ck8GvVQ9E

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer
GlobalAssocChangedCounter = 0x00000027(39)

It adds the following registry keys as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.Ck8GvVQ9E

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Ck8GvVQ9E

HKEY_LOCALMACHINE\SOFTWARE\Classes\
Ck8GvVQ9E\DefaultIcon

It changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
WallPaper = %ProgramData%\Ck8GvVQ9E.bmp

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = 10

It sets the system's desktop wallpaper to the following image:

  • %Program Data%\Ck8GvVQ9E.bmp

Process Termination

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

  • agntsvc
  • dbeng50
  • dbsnmp
  • encsvc
  • excel
  • firefox
  • infopath
  • isqlplussvc
  • msaccess
  • mspub
  • mydesktopqos
  • mydesktopservice
  • notepad
  • ocautoupds
  • ocomm
  • ocssd
  • onenote
  • oracle
  • outlook
  • powerpnt
  • sqbcoreservice
  • sql
  • steam
  • synctime
  • tbirdconfig
  • thebat
  • thunderbird
  • visio
  • winword
  • wordpad
  • xfssvccon

Other Details

This Ransomware does the following:

  • If not executed with admin rights, it will attempt relaunch itself as admin by elevating its privileges via bypassing UAC.
  • It encrypts fixed, removable, and network drives
  • It deletes files in recycle bin folder for removable and fixed drives
  • It uses WQL to delete shadow copies
  • It terminates if the machine has the following system language:
    • Arabic (Syria)
    • Armenian
    • Azeri (Cyrillic)
    • Azeri (Latin)
    • Belarusian
    • Georgian
    • Kazakh
    • Kyrgyz (Cyrillic)
    • Romanian (Moldova)
    • Russian
    • Russian (Moldova)
    • Tajik
    • Tatar
    • Turkmen
    • Ukrainian
    • Uzbek (Cyrillic)
    • Uzbek (Latin)
  • It deletes services with the following strings:
    • backup
    • GxBlr
    • GxCIMgr
    • GxCVD
    • GxFWD
    • GxVss
    • memtas
    • mepocs
    • msexchange
    • sophos
    • sql
    • svc$
    • veeam
    • vss
  • It deletes the following services:
    • WdBoot
    • WdFilter
    • WdNisDrv
    • WdNisSvc
    • WinDefend
    • wscsvc
    • sppsvc
    • Sense
    • SecurityHealthService
  • Change the icon of encrypted file with %ProgramData%\Ck8GvVQ9E.ico

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

Ransomware Routine

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

  • autorun.inf
  • boot.ini
  • bootfont.bin
  • bootsect.bak
  • d3d9caps.dat
  • desktop.ini
  • GDIPFONTCACHEV1.DAT
  • iconcache.db
  • ntldr
  • ntuser.dat
  • ntuser.dat.log
  • ntuser.ini
  • thumbs.db

It avoids encrypting files found in the following folders:

  • $recycle.bin
  • $windows.~bt
  • $windows.~ws
  • all users
  • boot
  • config.msi
  • default
  • intel
  • microsoft
  • msocache
  • perflogs
  • program files
  • program files (x86)
  • programdata
  • public
  • system volume information
  • tor browser
  • windows
  • windows.old
  • x64dbg

It renames encrypted files using the following names:

  • {Random Characters}.Ck8GvVQ9E

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

  • {Encrypted Directory}\Ck8GvVQ9E.README.txt

It avoids encrypting files with the following file extensions:

  • 386
  • .adv
  • .ani
  • .bat
  • .bin
  • .cab
  • .cmd
  • .com
  • .cpl
  • .cur
  • .deskthemepack
  • .diagcab
  • .diagcfg
  • .diagpkg
  • .dll
  • .drv
  • .exe
  • .hlp
  • .hta
  • .icl
  • .icns
  • .ico
  • .ics
  • .idx
  • .key
  • .ldf
  • .lnk
  • .lock
  • .mod
  • .mpa
  • .msc
  • .msi
  • .msp
  • .msstyles
  • .msu
  • .nls
  • .nomedia
  • .ocx
  • .pdb
  • .prf
  • .ps1
  • .rom
  • .rtp
  • .scr
  • .search-ms
  • .shs
  • .spl
  • .sys
  • .theme
  • .themepack
  • .wpx

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 18.422.03
FIRST VSAPI PATTERN DATE: 03 May 2023
VSAPI OPR PATTERN File: 18.423.00
VSAPI OPR PATTERN Date: 04 May 2023

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

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
    • .Ck8GvVQ9E
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
    • Ck8GvVQ9E
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Ck8GvVQ9E\
    • DefaultIcon

Step 3

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_LOCAL_MACHINE\SOFTWARE\Classes\.Ck8GvVQ9E
    • (Default) = Ck8GvVQ9E
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Ck8GvVQ9E\DefaultIcon
    • (Default) = %ProgramData%Ck8GvVQ9E.ico
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersio
    • Explorer GlobalAssocChangedCounter = 0x00000027(39)

Step 4

Search and delete this file

[ 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.
  • %Program Data%\{4 random characters}.tmp
  • %Program Data%\Ck8GvVQ9E.bmp
  • %Program Data%\Ck8GvVQ9E.ico
  • %System Root%\{8 random characters}\{random}.tmp

Step 5

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %System Root%\{8 random characters}

Step 6

Scan your computer with your Trend Micro product to delete files detected as Ransom.PS1.LOCKBIT.AA. 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 7

Restore encrypted files from backup.

Step 8

Reset your Desktop properties

[ Learn More ]


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