Analysis by: Leidryn Saludez
 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 drops files as ransom note.

  TECHNICAL DETAILS

File Size: 946,176 bytes
File Type: EXE
Initial Samples Received Date: 05 Oct 2023
Payload: Creates files, Drops files, Displays message/message boxes, 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 drops the following files:

  • {Drive Letter}:\KeyForFiles\Key.secret → contains encrypted victim's information and master key for decryption
  • {Drive Letter}:\KeyForFiles\DecryptionKey.txt
  • C:\KeyForFiles\PublicKey.txt
  • E:\Rns for being rich\Enmity\Release\Enmity.pdb → project file

Other System Modifications

This Ransomware adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Enmity
ID = {Victim's ID}

Information Theft

This Ransomware accepts the following parameters:

  • {Drive Letter}:\

Other Details

This Ransomware does the following:

  • Upon execution, it shows a command line interface whereas it accepts parameters:
    • 1 → Full Encryption
    • 2 → Specific Directory Encryption (note that the sample file should be in the directory to be encrypted)
  • The information inside the Key.secret file for decryption are the following:
    • Victim ID
    • Amount of data Encrypted
    • Criminal email address
    • IP address
    • Date of Infection

Ransomware Routine

This Ransomware renames encrypted files using the following names:

  • {Random}-Mail[{BLOCKED}o@gmail.com ]ID-[{User's ID}].{Random 6-byte characters}

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

  • Enmity-Unlock-Guide.txt

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 18.740.04
FIRST VSAPI PATTERN DATE: 06 Oct 2023
VSAPI OPR PATTERN File: 18.741.00
VSAPI OPR PATTERN Date: 07 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:

     PE.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

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.
  • C:\KeyForFiles\Key.secret
  • C:\KeyForFiles\DecryptionKey.txt
  • C:\KeyForFiles\PublicKey.txt
  • E:\Rns for being rich\Enmity\Release\Enmity.pdb

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\Enmity
    • ID = {Victim's ID}

Step 6

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.ENMITY.THJOFBC. 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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