Analysis by: John Rainier Navato
ALIASES:

Gen:Variant.Ransom.Adhubllka.83 (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 drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size: 143,360 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 16 Apr 2024
Payload: Drops files, 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:

  • %System%cmd.exe /c vssadmin.exe delete shadows /all /quiet
  • %System%cmd.exe /c ping 127.0.0.1 -n 4 > nul & del {Malware File Name}.{Malware File Extension} - if selfdel parameter is used

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

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\SENATORMutex

Dropping Routine

This Ransomware drops the following files:

  • {Malware File Path}\SENATOR.txt → Contains log activities

Information Theft

This Ransomware accepts the following parameters:

  • -path → Used to specify the path to encrypt
  • -ratio → Used to specify the encryption ratio
  • -nomutex → Used to disable mutex creation
  • -nonetdrive → Used to disable encryption of network drives
  • -selfdel → Used to delete itself after execution

Other Details

This Ransomware does the following:

  • It sets the current process priority to highest
  • It empties the Recycled Bin
  • By default, it encrypts removable, fixed, and remote drives
  • It avoids encrypting files with the following file names:
    • autorun.inf
    • boot.ini
    • bootfont.bin
    • bootmgr
    • bootsect.bak
    • desktop.ini
    • iconcache.db
    • ntldr
    • ntuser.dat
    • ntuser.dat.log
    • ntuser.ini
    • SENATOR ENCRYPTED.TXT
    • SENATOR.TXT
    • thumbs.db

Ransomware Routine

This Ransomware avoids encrypting files found in the following folders:

  • $RECYCLE.BIN
  • $Windows.~bt
  • $windows.~ws
  • All Users
  • Boot
  • Config.Msi
  • Default
  • google
  • Intel
  • microsoft
  • Microsoft Visual Studio 16.0
  • MSOCache
  • PerfLogs
  • Public
  • System Volume Information
  • tor browser
  • Windows
  • windows nt
  • windows.old
  • yandex

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

  • {Original File Name}.{Original Extension}.EMAIL=senatorrans@gmail.com]ID=[{Decryption ID}].SENATOR

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

  • {Encrypted File Path}\SENATOR_ENCRYPTED.txt

It avoids encrypting files with the following file extensions:

  • .drv
  • .efi
  • .lnk
  • .msi
  • .SENATOR
  • .sys

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 19.308.02
FIRST VSAPI PATTERN DATE: 29 Apr 2024
VSAPI OPR PATTERN File: 19.309.00
VSAPI OPR PATTERN Date: 30 Apr 2024

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.XXPE50FFF080

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

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 File Path}\SENATOR_ENCRYPTED.txt
  • {Malware File Path}\SENATOR.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.BTCAZADI.THDBIBD. 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:


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