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Ransom.MSIL.BLCKDREAM.THJBEBC

November 30, 2023
 Analysis by: Raighen Sanchez
 ALIASES:

TR/Ransom.kudwl (ANTIVIR)

 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.

It encrypts files found in specific folders. It drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size:

127,488 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

25 Oct 2023

Payload:

Modifies system registry, 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 adds the following processes:

  • cmd.exe /c vssadmin.exe delete shadows /all /quiet → deletes shadow copies

Autostart Technique

This Ransomware modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
CurrentVersion\Run
SF = {malware path}\{malware filename}.exe

Other Details

This Ransomware does the following:

  • It does not encrypt files larger than 2GB.
  • It encrypts files in local, removable, and shared drives.

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • %Desktop%
  • %User Profile%\Favorites
  • %User Profile%\Downloads
  • %User Profile%\Documents
  • %User Profile%\Pictures
  • %User Profile%\Videos
  • %User Profile%\Music
  • {Available Drives}

(Note: %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\Desktop on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

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

  • ReadME-Decrypt

It avoids encrypting files found in the following folders:

  • C:\Windows

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

  • {original filename}.{original extension}.[affected system ID].[Blackdream01@zohomail.eu].BlackDream

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

  • {available drives}\ReadME-Decrypt.txt
  • %Desktop%\ReadME-Decrypt.txt

It avoids encrypting files with the following file extensions:

  • .BlackDream
  • .blackdream
  • .Blackdream
  • .blackDream
  • .exe
  • .dll

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.778.04

FIRST VSAPI PATTERN DATE:

25 Oct 2023

VSAPI OPR PATTERN File:

18.779.00

VSAPI OPR PATTERN Date:

26 Oct 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:

    •  TSPY.Win32.TRX.XXPE50FFF075

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\CurrentVersion\Run
    • SF = {malware path}\{malware filename}.exe

Step 6

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.

  • {available drives}\ReadME-Decrypt.txt
  • %Desktop%\ReadME-Decrypt.txt

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.MSIL.BLCKDREAM.THJBEBC. 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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