Ransom.Win32.XORIST.THLODBC


 ALIASES:

HEUR:Trojan-Dropper.Win32.Autoit.gen (KASPERSKY)

 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 encrypts files with specific file extensions. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

475,136 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

04 Dec 2023

Payload:

Displays message/message boxes, 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 and executes the following files:

  • %User Temp%\6TV8KH596tB4r6Q.exe → RegAsm.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • %Windows%\Microsoft.NET\Framework\v2.0.50727\RegAsm.exe

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

It injects codes into the following process(es):

  • %Windows%\Microsoft.NET\Framework\v2.0.50727\RegAsm.exe

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

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.xro

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
YWOOOABBZNYCLBEproce

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
YWOOOABBZNYCLBE\DefaultIcon

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
YWOOOABBZNYCLBE\shell

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
YWOOOABBZNYCLBE\shell\open

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
YWOOOABBZNYCLBE\shell\open\
command

It modifies the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Alcmeter = %User Temp%\6TV8KH596tB4r6Q.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.xro
(Default) = YWOOOABBZNYCLBE

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
YWOOOABBZNYCLBE
(Default) = CRYPTED!

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
YWOOOABBZNYCLBE\DefaultIcon
(Default) = %User Temp%\6TV8KH596tB4r6Q.exe,0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
YWOOOABBZNYCLBE\shell\open\
command
(Default) = %User Temp%\6TV8KH596tB4r6Q.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
upd = %User Temp%\{Malware Name}

Other Details

This Ransomware displays the following message boxes:

  • Asks for password for decryption (if %User Temp%\6TV8KH596tB4r6Q.exe already exists upon execution)



This Ransomware displays the following message boxes:






(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .zip
  • .rar
  • .7z
  • .tar
  • .gzip
  • .jpg
  • .jpeg
  • .psd
  • .cdr
  • .dwg
  • .max
  • .bmp
  • .gif
  • .png
  • .doc
  • .docx
  • .xls
  • .xlsx
  • .ppt
  • .pptx
  • .txt
  • .pdf
  • .djvu
  • .htm
  • .html
  • .mdb
  • .cer
  • .p12
  • .pfx
  • .kwm
  • .pwm
  • .1cd
  • .md
  • .mdf
  • .dbf
  • .odt
  • .vob
  • .ifo
  • .lnk
  • .torrent
  • .mov
  • .m2v
  • .3gp
  • .mpeg
  • .mpg
  • .flv
  • .avi
  • .mp4
  • .wmv
  • .divx
  • .mkv
  • .mp3
  • .wav
  • .flac
  • .ape
  • .wma
  • .ac3

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

  • .xro

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

  • It drops the following file(s) as ransom note:
    {Encrypted Directory}\HOW TO DECRYPT FILES.txt


  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.858.05

FIRST VSAPI PATTERN DATE:

04 Dec 2023

VSAPI OPR PATTERN File:

18.859.00

VSAPI OPR PATTERN Date:

05 Dec 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:

     TROJ.Win32.TRX.XXPE50FFF075

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.

  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.xro
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\YWOOOABBZNYCLBEproce
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\YWOOOABBZNYCLBE\DefaultIcon
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\YWOOOABBZNYCLBE\shell
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\YWOOOABBZNYCLBE\shell\open
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\YWOOOABBZNYCLBE\shell\open\command

Step 5

Restore this modified 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.

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  • Alcmeter = %User Temp%\6TV8KH596tB4r6Q.exe
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.xro
  • (Default) = YWOOOABBZNYCLBE
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\YWOOOABBZNYCLBE
  • (Default) = CRYPTED!
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\YWOOOABBZNYCLBE\DefaultIcon
  • (Default) = %User Temp%\6TV8KH596tB4r6Q.exe,0
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\YWOOOABBZNYCLBE\shell\open\command
  • (Default) = %User Temp%\6TV8KH596tB4r6Q.exe
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
  • upd = %User Temp%\{Malware Name}

Step 6

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.
  • %User Temp%\6TV8KH596tB4r6Q.exe

Step 7

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.XORIST.THLODBC. 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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