Analysis by: Karen Ivy Titiwa
ALIASES:

Trojan-Ransom.HiddenTear(IKARUS); Gen:Variant.Ransom.HiddenTear.3(BITDEFENDER)

 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 connects to certain websites to send and receive information. It terminates itself if it detects it is being run in a virtual environment.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 17446912 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 15 Apr 2021
Payload: Drops files, Steals information, Connects to URLs/IPs

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%\wall.jpg

(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 drops the following copies of itself into the affected system:

  • %User Startup%\HANTA.exe

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).)

Autostart Technique

This Ransomware creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
hanta_ransom = "%User Startup%\HANTA.exe"

Other System Modifications

This Ransomware modifies the following registry keys:

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = 1

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = 0

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Temp%\wall.jpg

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

  • %User Temp%\wall.jpg

Information Theft

This Ransomware gathers the following data:

  • machine GUID
  • computer name
  • username

Other Details

This Ransomware connects to the following website to send and receive information:

  • http://{BLOCKED}gbhdxgb.ueuo.com/current_mirror

It encrypts files with the following extensions:

  • .txt
  • .doc
  • .docx
  • .xls
  • .xlsx
  • .rtf
  • .csv
  • .ppt
  • .pptx
  • .odt
  • .jpg
  • .png
  • .csv
  • .sql
  • .mdb
  • .sln
  • .php
  • .asp
  • .aspx
  • .html
  • .xml
  • .psd
  • .dat
  • .bmp
  • .pdf
  • .log
  • .sq3
  • .zip
  • .cpp
  • .c
  • .h
  • .htm
  • .py
  • .py3
  • .sqlite

It terminates itself if it detects it is being run in a virtual environment.

It does the following:

  • It encrypts .txt files found in network shares

It terminates itself if any of the following file(s) are present:

  • SbieDll.dll

It terminates itself if any of the following user name(s) are found in the affected system:

  • WALKER
  • ARYA
  • arya
  • walker
  • LISA
  • Lisa

Ransomware Routine

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

  • .HANTA

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

  • %Desktop%\how_to_recover.txt

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.658.03
FIRST VSAPI PATTERN DATE: 15 Apr 2021
VSAPI OPR PATTERN File: 16.659.00
VSAPI OPR PATTERN Date: 16 Apr 2021

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.XXPE50FFF043

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

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • hanta_ransom = "%User Startup%\HANTA.exe"

Step 6

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.

  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • WallpaperStyle = From 1  to {default}
  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • TileWallpaper = From 0  to {default}
  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • Wallpaper = From %User Temp%\wall.jpg  to {default}

Step 7

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%\wall.jpg
  • %Desktop%\how_to_recover.txt

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.MSIL.HIDDENTEAR.AL. 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 9

Restore encrypted files from backup.


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