Analysis by: Patrick Noel Collado

ALIASES:

Ransom:Win32/FileCrypter.MB!MTB (Microsoft), NetTool.Win32.TorTool.cta (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

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 executes then deletes itself afterward.

  TECHNICAL DETAILS

File Size: 494,592 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 06 Nov 2020
Payload: Connects to URLs/IPs, Displays message/message boxes, Steals information, 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:

  • {Malware Path}\{Malware Name}.log
  • {Malware Path}\tor-lib.dll -> detected as TROJ_GEN.R049C0PK120

It adds the following processes:

  • schtasks /Create /SC MINUTE /TN "Mouse Application" /TR "{Malware Path}\{Malware Name}.exe" /f
  • wmic SHADOWCOPY DELETE
  • wbadmin DELETE SYSTEMSTATEBACKUP
  • bcdedit.exe / set{ default } bootstatuspolicy ignoreallfailures
  • bcdedit.exe / set{ default } recoveryenabled No
  • cmd.exe /C schtasks /Delete /TN "Mouse Application" /f
  • cmd.exe /C ping 1.1.1.1 -n 1 -w 3000 > Nul & Del /f /q "{Malware Path}"

It executes then deletes itself afterward.

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

  • svchost

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Mouse Application = {Malware Path}\{Malware Name}.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Notification = "%System%\notepad.exe" "%Application Data%\Microsoft\Windows\Network Shortcuts\HOW TO RESTORE FILES.TXT"

Other System Modifications

This Ransomware modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
CLSID\{645FF040-5081-101B-9F08-00AA002F954E}\DefaultIcon
(Default) = C:\Windows\System32\imageres.dll,-55

Process Termination

This Ransomware terminates the following processes if found running in the affected system's memory:

  • Processes that keep a file open during encryption

Information Theft

This Ransomware gathers the following data:

  • Computer Name
  • User Name
  • CPU Info

Other Details

This Ransomware connects to the following URL(s) to get the affected system's IP address:

  • api.ipify.org

It connects to the following possibly malicious URL:

  • elb097307-934924932.us-east-1.elb.{BLOCKED}ws.com
  • nagano-19599.{BLOCKED}ssl.com
  • {BLOCKED}zjibibtcgb.onion/input

It does the following:

  • It empties the recycling bin
  • Checks if the machine name and will show the following if the machine name is WIN-295748OMAKG:

Ransomware Routine

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

  • Cheat
  • Notepad
  • x96dbg
  • Hex Editor
  • Windows
  • ProgramData
  • Microsoft
  • System

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

  • .mouse

It leaves text files that serve as ransom notes containing the following text:

  • {Encrypted Folder}\HOW TO RESTORE FILES.TXT
  • %Application Data%\Microsoft\Windows\Network Shortcuts\HOW TO RESTORE FILES.TXT

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.334.07
FIRST VSAPI PATTERN DATE: 06 Nov 2020
VSAPI OPR PATTERN File: 16.335.00
VSAPI OPR PATTERN Date: 07 Nov 2020

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.XXPE50FFF038

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

Identify and terminate files detected as Ransom.Win32.REGRETLOCKER.A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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\Microsoft\Windows\CurrentVersion\Run
    • Mouse Application = {Malware Path}\{Malware Name}.exe

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Notification = "C:Windows\System32\notepad.exe" "%Application Data%\Microsoft\Windows\Network Shortcuts\HOW TO RESTORE FILES.TXT"

Step 6

Restore this modified 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\Microsoft\Windows\CurrentVersion\Explorer\CLSID\{645FF040-5081-101B-9F08-00AA002F954E}\DefaultIcon
    • C:\Windows\System32\imageres.dll,-55

Step 7

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.
  • {Malware Path}\{Malware Name}.log
  • {Malware Path}\tor-lib.dll
  • {Encrypted Folder}\HOW TO RESTORE FILES.TXT
  • %Application Data%\Microsoft\Windows\Network Shortcuts\HOW TO RESTORE FILES.TXT

Step 8

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.REGRETLOCKER.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 9

Restore encrypted files from backup.


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