Worm.Win32.AUTORUN.NIAR

 Analysis by: John Rainier Navato

 ALIASES:

Worm:Win32/Nuj.B (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

This Worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

343,040 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

29 Jun 2021

Payload:

Connects to URLs/IPs, Drops files, Modifies system registry, Downloads files

Arrival Details

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

  • {Available Drive}\SystemVolumeInformation\System.exe

It drops the following copies of itself into the affected system and executes them:

  • %System%\taskmg.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It drops the following files:

  • %System%\sys1.ini ← created by svhist.exe
  • %System%\about.txt
  • %System%\julysoft.exe ← later renamed to cnfmon.exe
  • {Available Drive}\Autorun.inf ← executes dropped copy in {Available Drive}\SystemVolumeInformation\System.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It drops and executes the following files:

  • %System%\spool.exe ← detected as Worm.Win32.AUTORUN.NIAR, adds and starts WindowsDriver service, ensures that taskmg.exe is running
  • %System%\svhist.exe ← detected as Worm.Win32.AUTORUN.NIAR, downloads julysoft.exe and renames it to cnfmon.exe, drops %System%\about.txt and %System%\sys1.ini
  • %System%\cnfmon.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

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

  • julychina ← added by taskmg.exe
  • shengjik ← added by svhist.exe

Other System Modifications

This Worm adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WindowsDriver
DisplayName = WindowsDriver

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WindowsDriver
ImagePath = %System%\spool.exe

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WindowsDriver
Start = 2

It adds the following registry keys as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services
WindowsDriver =

Download Routine

This Worm connects to the following URL(s) to download its component file(s):

  • http://{BLOCKED}ft.cn/data/data.html

It saves the files it downloads using the following names:

  • %Temporay Internet Files%\Content.IE5\{8 Random Characters}\data[1].htm

As of this writing, the said sites are inaccessible.

Other Details

This Worm does the following:

  • It adds and runs the following services:
    • DisplayName: WindowsDriver
      ImagePath: %System%\spool.exe
      Start: 2

    (Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.610.03

FIRST VSAPI PATTERN DATE:

03 Aug 2023

VSAPI OPR PATTERN File:

18.611.00

VSAPI OPR PATTERN Date:

04 Aug 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

Restart in Safe Mode

[ Learn More ]

Step 4

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\SYSTEM\CurrentControlSet\Services\WindowsDriver
    • DisplayName = WindowsDriver
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WindowsDriver
    • ImagePath =  %System%\spool.exe
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WindowsDriver
    • Start = 2

Step 5

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • WindowsDriver

Step 6

Disable this malware service

[ Learn More ]
  • WindowsDriver

Step 7

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.
  • %System%\taskmg.exe
  • %System%\spool.exe
  • %System%\svhist.exe
  • %Temporay Internet Files%\Content.IE5\{8 Random Characters}\data[1].htm
  • %System%\sys1.ini
  • %System%\julysoft.exe
  • %System%\cnfmon.exe
  • %System%\about.txt
  • {Available Drive}\Autorun.inf
  • {Available Drive}\SystemVolumeInformation\System.exe

Step 8

Search and delete this folder

[ 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.
  • {Available Drive}\SystemVolumeInformation

Step 9

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.Win32.AUTORUN.NIAR. 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.


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