Ransom.Win32.MAZE.G

December 12, 2019
 Analysis by: Arianne Grace Dela Cruz
 ALIASES:

HEUR:Downloader.NSIS.Xiazai.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.

However, as of this writing, the said sites are inaccessible.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

455,168 bytes

File Type:

DLL

Initial Samples Received Date:

09 Dec 2019

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:

  • %User Temp%\000.bmp
  • %All Users Profile%\data1.tmp

(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).. %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:

  • C:\ww\..\Windows\py\spje\ilso\..\..\..\system32\eq\..\wbem\ar\..\wmic.exe" shadowcopy delete

Other System Modifications

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

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Temp%\000.bmp

Other Details

This Ransomware connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.114.11/atu.html?youd=0h&cod=65jbu65
  • {BLOCKED}.{BLOCKED}.114.31/view/update/fgo.html?wx=v76n3r
  • {BLOCKED}.{BLOCKED}.114.38/logout/webauth/jp.shtml?h=6c60&ivh=buuptt4&fl=7&bsy=k7
  • www.{BLOCKED}.{BLOCKED}.114.79/update/fsgapr.asp?hd=824g4n1qp8&tyx=nod866x3
  • {BLOCKED}.{BLOCKED}.114.79/update/fsgapr.asp?hd=824g4n1qp8&tyx=nod866x3
  • {BLOCKED}.{BLOCKED}.114.4/x.do
  • {BLOCKED}.{BLOCKED}.114.11/transfer/csilwttrk.cgi

However, as of this writing, the said sites are inaccessible.

Ransomware Routine

This Ransomware appends the following extension to the file name of the encrypted files:

  • {Original File Extension}.{Random Extension}

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

  • {Encrypted Directory}\DECRYPT-FILES.txt

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.548.08

FIRST VSAPI PATTERN DATE:

09 Dec 2019

VSAPI OPR PATTERN File:

15.549.00

VSAPI OPR PATTERN Date:

10 Dec 2019

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.XXPE50FFF033 

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 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%\000.bmp
  • %All Users Profile%\data1.tmp
  • {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.G. 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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