Worm.Win32.VBNA.AB

 Analysis by: John Rey Canon

 ALIASES:

Win32.Worm.Wbna.Efup (Tencent); Worm.Win32.WBNA.nst (Kaspersky); Worm.Win32.VB (Ikarus)

 PLATFORM:

Windows

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

  • 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.

  TECHNICAL DETAILS

File Size:

147,456 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

27 May 2019

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 creates the following folders:

  • D:\System Volume

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
Dimon = "D:\System Volume\Adobe!.exe"

Other System Modifications

This Worm adds the following registry keys:

HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
f\f

HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
;net\[ONeShot]

It adds the following registry entries:

HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
f\f
f = ""

HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
;net\[ONeShot]
net; = "1"

Dropping Routine

This Worm drops the following files:

  • D:\System Volume\Adobe!.exe
  • {Drive Letter}:\{Malware Filename}.exe

Other Details

This Worm connects to the following possibly malicious URL:

  • http://smtp.{BLOCKED}l.com

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.136.04

FIRST VSAPI PATTERN DATE:

27 May 2019

VSAPI OPR PATTERN File:

15.137.00

VSAPI OPR PATTERN Date:

28 May 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

Restart in Safe Mode

[ Learn More ]

Step 3

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\Software\VB and VBA Program Settings
    • f
  • In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\;net
    • [ONeShot]

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
    • Dimon = "D:\System Volume\Adobe!.exe"
  • In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\f\f
    • f = ""
  • In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\;net\[ONeShot]
    • net; = "1"

Step 5

Search and delete these components

[ Learn More ]
There may be some components 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.
  • D:\System Volume\Adobe!.exe
  • {Drive Letter}:\{Malware Filename}.exe

Step 6

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.
  • D:\System Volume

Step 7

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


Did this description help? Tell us how we did.