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Ransom.Win32.BLACKCAT.SMYMDED

November 17, 2023
 Analysis by: Raymart Christian Yambot
 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 encrypts files with specific file extensions. It drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size:

34,562,048 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Nov 2023

Payload:

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:

  • {Malware File Path}\{Malware File Name} {launch key}
  • "cmd" /c "wmic.exe Shadowcopy Delete"
  • "cmd" /c "vssadmin.exe Delete Shadows /all /quiet"

Other Details

This Ransomware does the following:

  • It contains an embedded Impacket toolkit
  • Adds the following service:
    • {Malware File Path}\{Malware File Name} {launch key} → Terminates afterwards

It accepts the following parameters:

  • {launch string} → required to proceed to its encryption routine
    • -p | --path {Directory}→ Path to encrypt.
    • -f | --paths-file {File path}→ Load path from file.
    • -o | --override-credentials {User credentials} → Oerride config credentials.
    • -R | --disable-recursion → Disable encrypting sub-folders within the specified directory in "--path" parameter.
    • -N | --disable-network → Disable automatic network discovery.
    • -K | --disable-elevate-to-system → Do not attempt to elevate acces token to system.
    • -E | --disable-self-propagation → Disable network self propagation.
    • -s | --suspend → Initialize and wait for incoming client connections.
    • -w | --watch {Time} → Server will remain active after execution and repeat discovery on given time.
    • -v | --verbose → Print log to console.
    • -X | --self-destuct → Delete file after execution.
    • -h | --help → Print help information.
    • -c | client → Connect to local server.
    • -e | exec → Start Remote Server.
    • -t | toolkit → Various tools.
    • help → Print help information.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .log
  • .docx
  • .docm
  • .dotx
  • .dotm
  • .vmxf
  • .vmdk
  • .vmem
  • .vswp
  • .vmsn
  • .vmsd
  • .vmx
  • .iso
  • .zip
  • .txt
  • .nvram
  • .backup
  • .lock
  • .tmp
  • .sql
  • .doc
  • .rtf
  • .xls
  • .jpg
  • .jpeg
  • .png
  • .gif
  • .webp
  • .tiff
  • .psd
  • .raw
  • .bmp
  • .pdf
  • .odt
  • .xlsx
  • .xlsm
  • .xltx
  • .xltm
  • .xlsb
  • .xlam
  • .ods
  • .pptx
  • .pptm
  • .ptox
  • .potm
  • .ppsx
  • .ppsm
  • .odp
  • .mdf

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

  • \NTUSER.DAT
  • \autorun.inf
  • \boot.ini
  • \desktop.ini
  • \Program Files\Common Files\System
  • \Program Files\Internet Explorer
  • \Program Files\ModifiableWindowsApps
  • \Program Files\Uninstall Information
  • \Program Files\Windows Defender
  • \Program Files\Windows Media Player
  • \Program Files\Windows Photo Viewer
  • \Program Files\Windows Security
  • \Program Files\WindowsPowerShell
  • \Program Files(x86)\Common Files
  • \Program Files(x86)\Internet Explorer
  • \Program Files(x86)\Microsoft\*Edge*
  • \Program Files(x86)\Microsoft\Temp
  • \Program Files(x86)\Microsoft.NET
  • \Program Files(x86)\Windows Defender
  • \Program Files(x86)\Windows Mail
  • \Program Files(x86)\Windows NT
  • \Program Files(x86)\Windows Security
  • \Program Files(x86)\Windows Sidebar
  • \Program Files(x86)\WindowsPowerShell
  • \ProgramData\regid.*.com.microsoft
  • \ProgramData\Microsoft\Device Stage
  • \ProgramData\Microsoft\DeviceSync
  • \ProgramData\Microsoft\Diagnosis
  • \ProgramData\Microsoft\EdgeUpdate
  • \ProgramData\Microsoft\Event Viewer
  • \ProgramData\Microsoft\IdentityCRL
  • \ProgramData\Microsoft\NetFramework
  • \ProgramData\Microsoft\Provisioning
  • \ProgramData\Microsoft\SmsRouter
  • \ProgramData\Microsoft\Spectrum
  • \ProgramData\Microsoft\Speech_OneCore
  • \ProgramData\Microsoft\StorageHealth
  • \ProgramData\Microsoft\WindowsNT
  • \ProgramData\Microsoft\WinMSIPC
  • \ProgramData\Packages\USOPrivat
  • \ProgramData\Packages\USOShared
  • \ProgramData\Packages\Microsoft
  • \Program Files (x86)\Common Files\Microsoft Shared
  • \Program Files (x86)\Windows MultimediaPlatform
  • \ProgramData\Packages\WindowsHolographicDevices
  • \Program Files\Common Files\Services
  • \AppData\Local\Microsoft\GameDVR
  • \AppData\Local\Packages\Microsoft
  • \AppData\Local\Packages\MicrosoftWindows
  • \AppData\Local\Packages\Internet Explorer
  • \AppData\Local\Packages\Internet Explorer

It avoids encrypting files found in the following folders:

  • \windows.old
  • \PerfLogs
  • \ProgramData
  • /bin
  • /sbin
  • /boot
  • /cdrom
  • /etc
  • /lib
  • /proc
  • /root
  • /run
  • /srv
  • /sys
  • /tmp
  • /usr

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

  • {original file name}.{original extension}.{random characters}.kirgnl6

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

  • {Encrypted Directory}/{Random Characters}.txt

It avoids encrypting files with the following file extensions:

  • .msc0h
  • .dll
  • .sys
  • .lock
  • .msu
  • .lnk
  • .tmp

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.454.08

FIRST VSAPI PATTERN DATE:

19 May 2023

VSAPI OPR PATTERN File:

18.455.00

VSAPI OPR PATTERN Date:

20 May 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:

    • Troj.Win32.TRX.XXPE50FFF074

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, and then 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.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\{Malware name}

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.  
  • {Encrypted Directory}/{Random Characters}.txt

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.BLACKCAT.SMYMDED. 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 7

Restore encrypted files from backup.


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