Analysis by: Leidryn Saludez
ALIASES:

HEUR:Trojan-Ransom.Win32.Encoder.gen (KASPERSKY)

 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 requires being executed with a specific argument/parameter, an additional component, or in a specific environment in order to proceed with its intended routine.

  TECHNICAL DETAILS

File Size: 3,349,328 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 17 Oct 2023
Payload: Drops files, Modifies system registry

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:

  • %User Profile%\Documents\wwP51\{Malware Name}.exe ← copy of itself
  • %User Profile%\Documents\wwP51\config.ini

(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 creates the following folders:

  • %User Profile%\Documents\wwP51
  • %User Profile%\Documents\wwP51\driver
  • %User Profile%\Documents\wwP51\service
  • %User Profile%\Documents\wwP51\tools

(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).)

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
wwP51Ser = %User Profile%\Documents\wwP51\service\wwP51Ser.exe → Automatic Execution of required component

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Print\
Printers
wwP51 = %User Profile%\Documents

Other Details

This Ransomware requires being executed with a specific argument/parameter, an additional component, or in a specific environment in order to proceed with its intended routine.

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 18.762.04
FIRST VSAPI PATTERN DATE: 17 Oct 2023
VSAPI OPR PATTERN File: 18.763.00
VSAPI OPR PATTERN Date: 18 Oct 2023

Step 1

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 2

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 3

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • wwP51Ser = %User Profile%\Documents\wwP51\service\wwP51Ser.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Print\Printers
    • wwP51 = %User Profile%\Documents

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.
  • %User Profile%\Documents\wwP51\{Malware Name}.exe
  • %User Profile%\Documents\wwP51\config.ini

Step 5

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.  
  • %User Profile%\Documents\wwP51
  • %User Profile%\Documents\wwP51\driver
  • %User Profile%\Documents\wwP51\service
  • %User Profile%\Documents\wwP51\tools

Step 6

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.ENCODER.NR. 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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