Analysis by: Alyssa Christelle Ramos
 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

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.

It encrypts files with specific file extensions.

  TECHNICAL DETAILS

File Size: 336,896 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 09 Jun 2020
Payload: 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 Subfolder Path}\{Malware Folder Name}0.txt - log file
  • {Malware Subfolder Path}\{Malware Folder Name}count.txt - log file

It adds the following processes:

  • bcdedit.exe /deletevalue {current} safeboot
  • cmd.exe /C shutdown /r /f /t 0
  • cmd /C sc config locloc start= disabled

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\tomnon
keyM = {Random Characters}

HKEY_LOCAL_MACHINE\tomnon
keyM = {Random Characters}

Other Details

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\tomnon

HKEY_LOCAL_MACHINE\tomnon

It does the following:

  • It only encrypts files in Fixed Drives
  • Must be executed with an argument to perform its intended routine:
    • {Malware FIlename}.exe runner

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.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .3dm
  • .aspx
  • .bak
  • .bck
  • .bkf
  • .cpg
  • .csv
  • .dbf
  • .doc
  • .docx
  • .dwg
  • .jpeg
  • .jpg
  • .ldf
  • .mdb
  • .mdf
  • .opr
  • .ova
  • .pdf
  • .png
  • .ppt
  • .pptx
  • .prj
  • .psd
  • .pst
  • .rar
  • .raw
  • .rtf
  • .rui
  • .rvb
  • .sbn
  • .sbx
  • .shp
  • .shx
  • .sql
  • .txt
  • .vb
  • .vdi
  • .vhd
  • .vhdk
  • .vib
  • .vmdk
  • .xls
  • .xlsx
  • .xml
  • .zip

It avoids encrypting files with the following strings in their file name:

  • ProgramData
  • Windows
  • bootmgr
  • $WINDOWS.~BT
  • Windows.old
  • Temp
  • Program Files
  • Program Files (x86)
  • AppData
  • $Recycle.Bin

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

  • .ment

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.924.03
FIRST VSAPI PATTERN DATE: 11 Jun 2020
VSAPI OPR PATTERN File: 15.925.00
VSAPI OPR PATTERN Date: 12 Jun 2020

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

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry key

[ 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\tomnom
    • HKEY_LOCAL_MACHINE\tomnon

Step 5

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.
  • {Malware Subfolder Path}\{Malware Folder Name}0.txt
  • {Malware Subfolder Path}\{Malware Folder Name}count.txt

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.LOCMENT.YMAF-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 this Knowledge Base page for more information.

Step 7

Restore encrypted files from backup.

Step 8

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.LOCMENT.YMAF-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:


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