VBS_DUNIHI.BA


 ALIASES:

Worm:VBS/Jenxcus.AP (Microsoft), VBS.Dunihi (Norton), VBS/Dunihi.EB (AntiVir), ASP/BackDoor (AVG)

 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 drops copies of itself in all removable drives.

It executes commands from a remote malicious user, effectively compromising the affected system.

It steals system information. It retrieves specific information from the affected system.

It sends the information it gathers to remote users via HTTP Post.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size:

33,435 bytes

File Type:

VBS

Memory Resident:

Yes

Payload:

Connects to URLs/IPs, Drops files, Compromises system security

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.

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 name} = "wscript.exe //B "%User Temp%\{malware name}.vbs""

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{malware name} = "wscript.exe //B "%User Temp%\{malware name}.vbs""

It drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\{malware name}.vbs - copy of itself

(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, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\{malware name}

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\{malware name}
(Default) = "{true or false}"

Propagation

This worm drops copies of itself in all removable drives.

Backdoor Routine

This worm executes the following commands from a remote malicious user:

  • execute code
  • update itself
  • uninstall itself
  • download file

Dropping Routine

This worm drops the following files:

  • {removable drive letter}:\{file name}.lnk - shortcut to the file it hides

Download Routine

This worm connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}2.{BLOCKED}p.biz:3440/is-sending

It saves the files it downloads using the following names:

  • %User Temp%\{file name}.{extension}

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Information Theft

This worm steals system information.

It retrieves the following information from the affected system:

  • volume serial information
  • computer name
  • user name
  • operating system
  • antivirus products
  • whether the system is infected via usb or not

Drop Points

This worm sends the information it gathers to remote users via HTTP Post.

Other Details

This worm connects to the following website to send and receive information:

  • http://{BLOCKED}2.{BLOCKED}p.biz:3440/is-ready

It sets the attributes of the following file(s) to Hidden and System:

  • {removable drives}:\{malware name}.vbs
  • {removable drives}:\{filename}.{any extension except lnk}

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.286.02

FIRST VSAPI PATTERN DATE:

18 Sep 2013

VSAPI OPR PATTERN File:

10.287.00

VSAPI OPR PATTERN Date:

19 Sep 2013

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 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
    • {malware name} = "wscript.exe //B "%User Temp%\{malware name}.vbs""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {malware name} = "wscript.exe //B "%User Temp%\{malware name}.vbs""

Step 5

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 name}

Step 6

Search and delete these files

[ 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.  
  • .lnk files created by the malware in the root directory of removable drives, i.e. {removable drive}:\{filename}.lnk

Step 7

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

Set system to display all hidden files and folders

[ Learn More ]

Step 9

  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 10

Scan your computer with your Trend Micro product to delete files detected as VBS_DUNIHI.BA. 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 11

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. DATA_GENERIC
  • In the Look In drop-down list, select My Computer then press Enter.
  • Once located, select the file then press SHIFT+DELETE to delete it.
    *Note: The file name input box title varies depending on the Windows version (e.g. Search for files or folders named or All or part of the file name.).
  • • For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

    1. Open a Windows Explorer window.
      • For Windows Vista, 7, and Server 2008 users, click Start>Computer.
      • For Windows 8, 8.1, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
    2. In the Search Computer/This PC input box, type:
      DATA_GENERIC
    3. Once located, select the file then press SHIFT+DELETE to delete it.
      *Note: Read the following Microsoft page if these steps do not work on Windows 7.

    NOTES:

    The process to be terminated is the wscript.exe that runs .vbs scripts.

    For every .lnk file to be deleted, restore the file attribute of its target.

    .LNK to delete:

    • {removable drive}:\{file name}.lnk

    Reset Hidden and System Attribute:

    • {removable drive}\{file name}.{extension}


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