Analysis by: Emilio Marcel Garcia

ALIASES:

Ransom:Win32/Maze.PA!MTB (MICROSOFT); Trojan-Ransom.Win32.Gen.woq (KASPERSKY)

 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: Dropped by other malware, 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 generates a beeping sound.

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

  TECHNICAL DETAILS

File Size: 615,624 bytes
File Type: DLL
Memory Resident: No
Initial Samples Received Date: 19 Apr 2020
Payload: Displays graphics/image, Terminates processes, Collects system information, Connects to URLs/IPs, 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 the following files:

  • %All Users Profile%\memes.tmp

(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). )

It adds the following processes:

  • wmic shadowcopy delete

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

  • Global\{random characters} -> string is generated 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:

Process Termination

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

  • ida.exe
  • ida64.exe
  • x32dbg.exe
  • x64dbg.exe
  • python.exe
  • fiddler.exe
  • dumpcap.exe
  • procmon.exe
  • procexp.exe
  • procmon64.exe
  • procexp64.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
  • User Language
  • System Language
  • System Uptime

Stolen Information

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

  • http://{IP}/{Strings}/{Random String}.{Extensions} where
    • IP:
      • {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
    • Strings:
      • news
      • login
      • register
      • logout
      • edit
      • content
      • private
      • messages
      • account
      • view
      • webauth
      • webaccess
      • archive
      • forum
      • post
      • signin
      • signout
      • update
      • support
      • ticket
      • task
      • tracker
      • analytics
      • check
      • checkout
      • payout
      • withdrawal
      • sepa
      • create
      • transfer
      • wire
    • Extensions :
      • .php
      • .asp
      • .aspx
      • .cgi
      • .jsp
      • .jspx
      • .action
      • .html
      • .phtml
      • .shtml

Other Details

This Ransomware generates a beeping sound.

It does the following:

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

It does not proceed to its malicious routine if it detects that it is being debugged.

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:

  • \ProgramFiles
  • :\Windows
  • \Games\
  • \Tor Browser\
  • \ProgramData\
  • \cache2\entries\
  • \Low\Content.IE5\
  • \User Data\Default\Cache\
  • \All Users
  • \IETldCache\
  • \Local Settings\
  • \AppData\Local
  • AhnLab
  • {GUID}

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

  • .{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: 15.814.02
FIRST VSAPI PATTERN DATE: 19 Apr 2020
VSAPI OPR PATTERN File: 15.815.00
VSAPI OPR PATTERN Date: 20 Apr 2020

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

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 3

Restart in Safe Mode

[ Learn More ]

Step 4

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.
  • %All Users Profile%\memes.tmp
  • %User Temp%\111.bmp
  • {Encrypted directory}\DECRYPT-FILES.txt

Step 5

Reset your Desktop properties

[ Learn More ]

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.MAZE.AC. 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 7

Restore encrypted files from backup.


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