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Worm.VBS.RUNNER.A

December 16, 2019
 Analysis by: Jay Garcia
 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Via physical/removable drives


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 does not have any backdoor routine.

  TECHNICAL DETAILS

File Size:

4,548 bytes

File Type:

VBS

Memory Resident:

Yes

Initial Samples Received Date:

13 Dec 2019

Payload:

Steals information

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:

  • C:\Windows\net.log <- contains gathered information
  • C:\Windows\{device name}.log <- contains gathered information

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft Office 2018 = wscript.exe /e:vbscript.encode C:\ProgramData\V29ybQ.jpg

Other System Modifications

This Worm modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Google\Chrome
IncognitoModeAvailability = 1

(Note: The default value data of the said registry entry is 0.)

It modifies the following registry entries to hide files with Hidden attributes:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 0

(Note: The default value data of the said registry entry is 1.)

Backdoor Routine

This Worm does not have any backdoor routine.

Information Theft

This Worm gathers the following data:

  • Connected devices/computers on the network
  • Drives
  • Directories
  • Shared Folders

Other Details

This Worm does the following:

  • It copies the file C:\ProgramData\Y2hyb21l.jpg to {Google Chrome path}\chrome.exe to replace the original google chrome executable
  • It renames the original chrome.exe to chromeold.exe
  • It drops copies of C:\ProgramData\Wallpaper.jpg in removable drives using the names of the folders located on the said drives as filenames. It then hides the original folders to trick users on opening the file.

NOTES:

Rootkit Capabilities

This Worm does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.559.00

FIRST VSAPI PATTERN DATE:

14 Dec 2019

VSAPI OPR PATTERN File:

15.560.00

VSAPI OPR PATTERN Date:

15 Dec 2019

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Microsoft Office 2018 = wscript.exe /e:vbscript.encode C:\ProgramData\V29ybQ.jpg

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\Windows\CurrentVersion\Explorer\Advanced
    • From: HideFileExt = 1
      To: HideFileExt = 0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome
    • From: IncognitoModeAvailability = 1
      To: IncognitoModeAvailability = 0

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.
  • C:\Windows\net.log
  • C:\Windows\{device name}.log

Step 7

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


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