VBS_DUNIHI.THHAFAI

 Analysis by: John Rey Canon

 ALIASES:

Worm:VBS/Jenxcus (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:

Propagates via flashdrives, Downloaded from the Internet, Dropped by other malware

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

It runs certain commands that it receives remotely from a malicious user. Doing this puts the affected computer and information found on the computer at greater risk.

It gathers certain information on the affected computer.

  TECHNICAL DETAILS

File Size:

20,236 bytes

File Type:

VBS

Memory Resident:

Yes

Initial Samples Received Date:

06 Sep 2018

Payload:

Collects system information, Drops files, Creates shortcuts

Arrival Details

This Worm arrives via removable drives.

It 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 copies of itself into the affected system:

  • %Application Data%\{Malware Filename}.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.)

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
{Malware Filename} = wscript.exe //B "%Application Data%\{Malware Filename}.vbs"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{Malware Filename} = wscript.exe //B "%Application Data%\{Malware Filename}.vbs"

It enables its automatic execution at every system startup by dropping the following copies of itself into the Windows Common Startup folder:

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

(Note: %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.)

Other System Modifications

This Worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\{Malware Filename}

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\{Malware Filename}
(Default) = {true/false} - {Date}

Propagation

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

  • {Infected Drive}:\{Malware Filename}.vbs

It creates shortcut files (.LNK) disguised as folders or files located on the affected drives pointing to the malware copy.

Backdoor Routine

This Worm executes the following command(s) from a remote malicious user:

  • "excecute" - Execute specified file
  • "update" - Update malware code and restart the malware
  • "uninstall" - Uninstall the malware
  • "send" - Download and run a file from the C&C server
  • "site-send" - Download and run a file
  • "recv" - Send a file to the C&C server
  • "enum-driver " - Send list of drives
  • "enum-faf" - Enumerate folders and files contained in a folder
  • "enum-process" - List running processes
  • "cmd-shell" - Execute a command using Command Prompt
  • "delete" - Delete a file or folder
  • "exit-process" - Terminate a process
  • "sleep" - Running script sleeps

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}coin.com:6969

Information Theft

This Worm gathers the following information on the affected computer:

  • OS name
  • Computer name
  • Current user name
  • Volume serial number
  • Installed AV products
  • USB spreading report

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.488.03

FIRST VSAPI PATTERN DATE:

06 Sep 2018

VSAPI OPR PATTERN File:

14.489.00

VSAPI OPR PATTERN Date:

07 Sep 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

Restart in Safe Mode

[ Learn More ]

Step 4

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_LOCAL_MACHINE\SOFTWARE
    • {Malware Filename}

Step 5

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) = {true/false} - {Date}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {Malware Filename} = wscript.exe //B "%Application Data%\{Malware Filename}.vbs"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {Malware Filename} = wscript.exe //B "%Application Data%\{Malware Filename}.vbs"

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.
  • %Application Data%\{Malware Filename}.vbs
  • %User Startup%\{Malware Filename}.vbs
  • {Infected Drive}:\{Malware Filename}.vbs
  • {Infected Directory}\{Original Foldername}.lnk

Step 7

  1. Open a command prompt.
    • For Windows 2000, Windows XP, and Windows Server 2003 users, click Start>Run. In the Search box, type CMD then press Enter.
    • For Windows Vista, Windows 7, and Windows Server 2008 users, click Start, type CMD in the Search input field then press Enter.
    • For Windows 8, Windows 8.1, and Windows Server 2012 users, right-click on the lower-left corner of the screen, click Command Prompt.
  2. In the CMD console, type the following:

    ATTRIB [+R | -R] [+A | -A ] [+S | -S] [+H | -H] [+I | -I] [drive:][path][file name] [/S [/D] [/L]]

    Where:
    + Sets an attribute.
    - Clears an attribute
    R Read-only file attribute
    A Archive file attribute
    S System file attribute
    H Hidden file attribute
    I Not content indexed file attribute
    [drive:][path][filename]
    Specifies a file or files for attrib to process
    /S Processes matching files in the current folder and all subfolders.
    /D Processes folders
    /L Work on the attributes of the Symbolic Link versus the target of the Symbolic Link
    Example:
    To unhide all files and folders (including subfolders) in drive D:
    ATTRIB –H D:\* /S /D
  3. Repeat Step 3 for folders and files in other drives or folders.

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as VBS_DUNIHI.THHAFAI. 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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