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Worm.VBS.AUTORUN.BKR

September 02, 2022
 Analysis by: Jeffrey Francis Bonaobra
 ALIASES:

Worm:VBS/Autorun.AG (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size:

12,304 bytes

File Type:

VBS

Memory Resident:

Yes

Initial Samples Received Date:

02 Sep 2022

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 the following files:

  • {Removable Drives}:\autorun.inf

It drops the following copies of itself into the affected system:

  • %System%\killVBS.vbs

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

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = %System%\userinit.exe, %System%\wscript.exe %System%\killVBS.vbs

Other System Modifications

This Worm modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Window Title =

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Start Page =

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
VBSFile
DefaultIcon = %SystemRoot%\System32\WScript.exe,2

Propagation

This Worm drops the following copy(ies) of itself in all removable drives:

  • {Removable Drives}:\killVBS.vbs

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.788.04

FIRST VSAPI PATTERN DATE:

02 Sep 2022

VSAPI OPR PATTERN File:

17.789.00

VSAPI OPR PATTERN Date:

03 Sep 2022

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\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Userinit = %System%\userinit.exe, %System%\wscript.exe %System%\killVBS.vbs

Step 5

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\Internet Explorer\Main
    • Window Title
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Start Page
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\VBSFile
    • DefaultIcon = %SystemRoot%\System32\WScript.exe,2

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.
  • {Removable Drives}:\killVBS.vbs
  • %System%\killVBS.vbs
  • {Removable Drives}:\autorun.inf

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.VBS.AUTORUN.BKR. 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 8

Scan your computer with your Trend Micro product to delete files detected as Worm.VBS.AUTORUN.BKR. 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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