PE_NESHTA.BMF

February 02, 2023
 Analysis by: Francesca Villasanta
 ALIASES:

Virus.Win32.Neshta.a (KASPERSKY); Win32:Phobos-D [Ransom] (AVAST)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Virus

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Virus 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:

98,816 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

31 Jan 2023

Arrival Details

This Virus 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 Virus drops the following copies of itself into the affected system:

  • %AppDataLocal%\{Malware Filename}.exe
  • %Common Startup%\{Malware Filename}.exe

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Common Startup% is the startup folder for all users, which is usually C:\Documents and Settings\All Users\Start Menu\Programs\Startup on Windows 2000, XP, and Server 2003, or C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

It drops the following files:

  • %User Temp%\{Generated ID}\{Malware Filename}.exe
  • %Windows%\svchost.com

It adds the following processes:

  • %User Temp%\{Generated ID}\{Malware Filename}.exe
  • %System%\cmd.exe
  • vssadmin  delete shadows /all /quiet
  • netsh  advfirewall set currentprofile state off
  • netsh  firewall set opmode mode=disable
  • wmic  shadowcopy delete
  • bcdedit  /set {default} bootstatuspolicy ignoreallfailures
  • bcdedit  /set {default} recoveryenabled nowbadmin  delete catalog -quiet
  • %System%\mshta.exe %Desktop%\info.hta

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\Desktop on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It creates the following folders:

  • %User Temp%\{Generated ID}

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{Malware Filename} = %AppDataLocal%\{Malware Filename}.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Malware Filename} = %AppDataLocal%\{Malware Filename}.exe

It drops the following file(s) in the Windows Common Startup folder to enable its automatic execution at every system startup:

  • %Common Startup%\{Malware Filename}.exe

(Note: %Common Startup% is the startup folder for all users, which is usually C:\Documents and Settings\All Users\Start Menu\Programs\Startup on Windows 2000, XP, and Server 2003, or C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Other System Modifications

This Virus modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
exefile\shell\open\
command
(Default) = %Windows%\svchost.com "%1" %*

Ransomware Routine

This Virus appends the following extension to the file name of the encrypted files:

  • .id[{Volume Serial Number}-{Generated ID}].[{BLOCKED}store@onionmail.org].faust

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

  • %Desktop%\info.hta
  • %Desktop%\info.txt
  • {Encrypted Drive}\info.hta
  • {Encrypted Drive}\info.txt

(Note: %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\Desktop on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.230.03

FIRST VSAPI PATTERN DATE:

01 Feb 2023

VSAPI OPR PATTERN File:

18.231.00

VSAPI OPR PATTERN Date:

02 Feb 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:

     TROJ.Win32.TRX.XXPE50FFF065

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

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_LOCAL_MACHINE\SOFTWARE\Classes\exefile\shell\open\command
    • (Default)

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {Malware Filename}=%AppDataLocal%\{Malware Filename}.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {Malware Filename}=%AppDataLocal%\{Malware Filename}.exe

Step 6

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 Temp%\{Generated ID}\{Malware Filename}.exe
  • %Windows%\svchost.com
  • %AppDataLocal%\{Malware Filename}.exe
  • %Common Startup%\{Malware Filename}.exe
  • %Desktop%\info.hta
  • %Desktop%\info.txt
  • {Encrypted Drive}\info.hta
  • {Encrypted Drive}\info.txt

Step 7

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 Temp%\{Generated ID}

Step 8

Scan your computer with your Trend Micro product to delete files detected as PE_NESHTA.BMF. 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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