Analysis by: Arvin Roi Macaraeg
ALIASES:

VBS/Dropper.aa (McAfee), HEUR:Trojan.Script.Agent.gen (Kaspersky)

 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.

  TECHNICAL DETAILS

File Size: 55,109 bytes
File Type: VBS
Memory Resident: No
Initial Samples Received Date: 15 Aug 2018

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 Drive Letter}:\nWPZJHPFOa.vbs
  • {Removable Drive Letter}:\{Malware Filename}.lnk
  • {Removable Drive Letter}:\nWPZJHPFOa.lnk
  • %Application Data%\nWPZJHPFOa.vbs
  • %User Startup%\nWPZJHPFOa.vbs

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows XP, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

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

  • %User Temp%\{Malware Filename}.vbs
  • %User Startup%\{Malware Filename}.vbs

(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, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows XP, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

It adds the following processes:

  • wscript.exe //B "C:\Users\{BLOCKED}er_732\AppData\Roaming\nWPZJHPFOa.vbs"
  • wscript.exe //B "C:\Users\{BLOCKED}~1\AppData\Local\Temp\{Malware Filename}.vbs"

Autostart Technique

This Worm creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
nWPZJHPFOa = "wscript.exe //B "C:\Users\{BLOCKED}er_732\AppData\Roaming\nWPZJHPFOa.vbs"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Malware Filename} = "wscript.exe //B "C:\Users\{BLOCKED}~1\AppData\Local\Temp\{Malware Filename}.vbs"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{Malware Filename} = "wscript.exe //B "C:\Users\{BLOCKED}~1\AppData\Local\Temp\{Malware Filename}.vbs"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
nWPZJHPFOa = "wscript.exe //B "C:\Users\{BLOCKED}er_732\AppData\Roaming\nWPZJHPFOa.vbs"

Other System Modifications

This Worm adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\{Malware Filename}
{Default} = "false - 8/30/2018"

HKEY_LOCAL_MACHINE\SOFTWARE\NWPZJHPFOA
{Default} = "false - 8/30/2018"

Propagation

This Worm drops the following copies of itself in all physical and removable drives:

  • {Removable Drive Letter}:\{Malware Filename}.vbs

Other Details

This Worm connects to the following possibly malicious URL:

  • http://odogwu.{BLOCKED}s.net:49986/is-ready
  • http://fud.{BLOCKED}pt.com:7744/is-ready

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.446.02
FIRST VSAPI PATTERN DATE: 16 Aug 2018
VSAPI OPR PATTERN File: 14.447.00
VSAPI OPR PATTERN Date: 17 Aug 2018

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 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

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\{Malware Filename}
    • {Default} = "false - 8/30/2018"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\NWPZJHPFOA
    • {Default} = "false - 8/30/2018"

Step 4

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 Drive Letter}:\nWPZJHPFOa.vbs
  • {Removable Drive Letter}:\{Malware Filename}.lnk
  • {Removable Drive Letter}:\nWPZJHPFOa.lnk
  • %Application Data%\nWPZJHPFOa.vbs
  • %User Startup%\nWPZJHPFOa.vbs

Step 5

Scan your computer with your Trend Micro product to delete files detected as VBS_DUNIHI.THHAFAH. 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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