Ransom.Win64.GROUNDE.THGOEBC

August 25, 2023
 Analysis by: Jemuel Igadna
 ALIASES:

Win64:Evo-gen [Trj](AVAST)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • 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:

149,504 bytes

File Type:

EXE

Memory Resident:

No

Payload:

Modifies system registry, Encrypts files, Displays message/message boxes

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:

  • {Encrypted Directory}\!!readme!!!.txt
  • {Malware File Path}\temp.cmd → Used to delete itself

It adds the following processes:

  • "%System%\vssadmin.exe" delete shadows /all /quiet
  • "%System%\net.exe" stop MSSQLSERVER /f /m
  • cmd /c temp.cmd {Malware File Path}/{Malware File Name}.{Malware Extension}

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows NT\Terminal Services
MaxDisconnectionTime = 1209600000

Ransomware Routine

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

  • !!readme!!!.txt
  • VIPinfo.txt

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

  • \microsoft\
  • \google\chrome
  • \mozilla\firefox
  • \opera\
  • C:\windows

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

  • {Encrypted Directory}\!!readme!!!.txt

It avoids encrypting files with the following file extensions:

  • sys
  • exe
  • dll
  • bat
  • bin
  • cmd
  • com
  • cpl
  • gadget
  • inf1
  • ins
  • inx
  • isu
  • job
  • jse
  • lnk
  • msc
  • msi
  • mst
  • paf
  • pif
  • rgs
  • scr
  • sct
  • shb
  • shs
  • u3p
  • vb
  • vbe
  • vbs
  • vbscript
  • ws
  • wsh
  • wsf

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.550.04

FIRST VSAPI PATTERN DATE:

05 Jul 2023

VSAPI OPR PATTERN File:

18.551.00

VSAPI OPR PATTERN Date:

06 Jul 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:

     
    • WORM.Win32.TRX.XXPE50FFF069

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.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services
    • MaxDisconnectionTime = 1209600000

Step 5

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.
  • {Encrypted Directory}\!!readme!!!.txt
  • {Malware File Path}\temp.cmd

Step 6

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win64.GROUNDE.THGOEBC. 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.


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