Analysis by: Joshua Paul Ignacio

ALIASES:

W32/Generik.KHTUKMX!tr.ransom (FORTINET); Trojan.SuspectCRC (IKARUS)

 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

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: 515,048 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 15 Jul 2020
Payload: Connects to URLs/IPs, Encrypts files, Steals information, Displays message/message boxes, 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 drops the following files:

  • %All Users Profile%\dump001.tmp
  • %User Temp%\111.bmp

(Note: %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). . %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:

  • "C:\taxyw\..\Windows\vn\qe\..\..\system32\ol\giog\..\..\wbem\ry\sq\..\..\wmic.exe" shadowcopy delete → deletes shadow copies

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\{Generated String from System Information}

Other System Modifications

This Ransomware changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Temp%\111.bmp

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

  • It detects the role of the machine infected and displays the appropriate string in the wallpaper:
    • a standalone server
    • a server in corporate network
    • a workstation in corporate network
    • a primary domain controller
    • a backup server
    • very valuable for you

Process Termination

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

  • dumpcap.exe
  • fiddler.exe
  • ida.exe
  • ida64.exe
  • procexp.exe
  • procexp64.exe
  • procmon.exe
  • procmon64.exe
  • python.exe
  • x32dbg.exe
  • x64dbg.exe

Information Theft

This Ransomware gathers the following data:

  • User Name
  • Computer Name
  • Process Integrity Level
  • Installed AVs
  • OS Name
  • Machine Role
  • Number of Drives
  • Shared Folders
  • System Language
  • System Uptime

Stolen Information

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

  • http://{IP Adress}/{String1}/{Random Characters}.{Extension}
    • where:
      • IP Address:
        • {BLOCKED}.{BLOCKED}.114.4
        • {BLOCKED}.{BLOCKED}.114.11
        • {BLOCKED}.{BLOCKED}.114.25
        • {BLOCKED}.{BLOCKED}.114.26
        • {BLOCKED}.{BLOCKED}.114.31
        • {BLOCKED}.{BLOCKED}114.32
        • {BLOCKED}.{BLOCKED}114.37
        • {BLOCKED}.{BLOCKED}.114.38
        • {BLOCKED}.{BLOCKED}.114.77
        • {BLOCKED}.{BLOCKED}114.79
      • String1:
        • account
        • analytics
        • archive
        • check
        • checkout
        • content
        • create
        • edit
        • forum
        • login
        • logout
        • messages
        • news
        • payout
        • post
        • private
        • register
        • sepa
        • signin
        • signout
        • support
        • task
        • ticket
        • tracker
        • transfer
        • update
        • view
        • webaccess
        • webauth
        • wire
        • withdrawal
      • Extension:
        • action
        • asp
        • aspx
        • cgi
        • html
        • jsp
        • jspx
        • php
        • phtml
        • shtml

Other Details

This Ransomware does the following:

  • It uses Windows Text-to-Speech functionality to play the following message:
    • {Username}! Alert! {Username}! Alert! Dear {Username}, your files have been encrypted by Maze Ransomware! Attention! You need to buy decryptor in order to restore the files.

Ransomware Routine

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

  • DECRYPT-FILES.txt
  • autorun.inf
  • boot.ini
  • desktop.ini
  • ntuser.dat
  • iconcache.db
  • bootsect.bak
  • ntuser.dat.log
  • thumbs.db
  • Bootfont.bin

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

  • :\Windows
  • \Games\
  • \Tor Browser\
  • \ProgramData\
  • \cache2\entries\
  • \Low\Content.IE5\
  • \User Data\Default\Cache\
  • \All Users
  • \IETldCache\
  • \Local Settings\
  • \AppData\Local
  • \Program Files

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

  • {Original File Name}.{Original File Extension}.{Random Characters}

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

  • {Encrypted Directory}\DECRYPT-FILES.txt

It avoids encrypting files with the following file extensions:

  • .lnk
  • .exe
  • .sys
  • .dll

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 16.114.07
FIRST VSAPI PATTERN DATE: 01 Jul 2020
VSAPI OPR PATTERN File: 16.115.00
VSAPI OPR PATTERN Date: 02 Jul 2020

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.XXPE50FFF036

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

Restart in Safe Mode

[ Learn More ]

Step 5

Search and delete these files

[ Learn More ]
There may be some component 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.
  • %All Users Profile%\dump001.tmp
  • %User Temp%\111.bmp
  • {Encrypted Directory}\DECRYPT-FILES.txt

Step 6

Reset your Desktop properties

[ Learn More ]

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.MAZE.AK. 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.


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