Analysis by: Thea Patrice Tajonera
ALIASES:

N/A

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • 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.

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

It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 60,416 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 21 May 2021
Payload: Connects to URLs/IPs, Displays graphics/image

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:

  • %AppDataLocal%\{Appended Extension}.ico
  • %ProgramData%\{Appended Extension}.BMP
  • %AllUsersProfile%\{Appended Extension}.BMP

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.{Appended Extension}
(Default) = {Appended Extension}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
{Appended Extension}\DefaultIcon
(Default) = %AppDataLocal%\{Appended Extension}.ico

Other Details

This Ransomware adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.{Appended Extension}

It connects to the following possibly malicious URL:

  • http://{BLOCKED}bestapp20.com:443

It does the following:

  • This Ransomware changes the desktop's wallpaper

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 Filename}.{Original Extension}.{Random Characters}

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

  • %System%\README.{Appended Extension}.TXT
  • {Encrypted Directory}\README.{Appended Extension}.TXT

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

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.402.08
FIRST VSAPI PATTERN DATE: 09 Dec 2020
VSAPI OPR PATTERN File: 16.403.00
VSAPI OPR PATTERN Date: 10 Dec 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.XXPE50FFF044

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_LOCAL_MACHINE\SOFTWARE\Classes\.{Appended Extension}
    • (Default) = {Appended Extension}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\{Appended Extension}\DefaultIcon
    • (Default) = %AppDataLocal%\{Appended Extension}.ico

Step 6

Delete this registry key

[ 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.

  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.{Appended Extension}

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.
  • %AppDataLocal%\{Appended Extension}.ico
  • %ProgramData%\{Appended Extension}.BMP
  • %AllUsersProfile%\{Appended Extension}.BMP
  • %System%\README.{Appended Extension}.TXT
  • {Encrypted Directory}\README.{Appended Extension}.TXT

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.DARKSIDE.SMYAAK-B. 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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