Analysis by: John Rainier Navato
 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 does not have any propagation routine.

It does not have any backdoor routine.

It does not have any information-stealing capability.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 11,776 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 22 Jan 2025
Payload: Encrypts files

Installation

This Ransomware drops a copy of itself in the following folders using different file names:

  • {Removable Drive or Network Drive Letter}:\Microsoft-USB-Security.exe

Propagation

This Ransomware does not have any propagation routine.

Backdoor Routine

This Ransomware does not have any backdoor routine.

Rootkit Capabilities

This Ransomware does not have rootkit capabilities.

Information Theft

This Ransomware does not have any information-stealing capability.

Other Details

This Ransomware does the following:

  • It encrypts all files found in available drives except for C:\ in which it only encrypts files in %User Profile% and its folders.

(Note: %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 does not exploit any vulnerability.

Ransomware Routine

This Ransomware avoids encrypting files found in the following folders:

  • %User Profile%\AppData

(Note: %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 drops the following file(s) as ransom note:

  • {Encrypted File Path}\Viper_README.RW-SK.txt

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 19.860.03
FIRST VSAPI PATTERN DATE: 25 Jan 2025
VSAPI OPR PATTERN File: 19.861.00
VSAPI OPR PATTERN Date: 26 Jan 2025

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.XXPE50FFF090

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}\Viper_README.RW-SK.txt
  • {Removable Drive or Network Drive Letter}:\Microsoft-USB-Security.exe

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.MSIL.VIPERKNIGHT.A. 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:

Step 6

Restore encrypted files from backup.


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