Analysis by: Ryan Gardo

ALIASES:

VBS/Agent.NDH(ESET-NOD32); HEUR:Worm.Script.Generic(Kaspersky); Worm.VBS.Agent(Ikarus)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 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: Via removable drives, 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 connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size: 30,581 bytes
File Type: VBS
Memory Resident: Yes
Initial Samples Received Date: 23 Feb 2015
Payload: Compromises system security, Steals information

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:

  • %User Temp%{malware filename}.vbs

(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.)

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 "%User Temp%\{malware filename}.vbs""

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
{malware filename} = "wscript.exe //B "%User Temp%\{malware filename}.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 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, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Other System Modifications

This worm adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\{Malware Filename}
(Default) = "{"true" or "false"} - {Installation Date}"

Propagation

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

  • {Removable Drive Letter}:\{malware filename}.vbs

It drops copies of itself in all removable drives.

Backdoor Routine

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

  • Execute files
  • Update itself
  • Uninstall itself
  • Download files
  • Upload files
  • Enumerate drivers
  • Enumerate files and folders
  • Enumerate processes
  • Perform remote shell
  • Delete files and folders
  • Terminate process
  • Sleep

It connects to the following websites to send and receive information:

  • http://jou7a.{BLOCKED}p.biz:1954/is-ready

Information Theft

This worm gathers the following data:

  • Computer name
  • Host name
  • OS Version

NOTES:

This malware drops the following shortcut pointing to its copy in all removable drive:

  • {Removable Drive Letter}:\{user files}.lnk - detected as LNK_DUNIHI.SMIX

It creates .LNK (shortcut) files using folder or file names found in removable drives. It then hides the original folder/file tricking users to click .LNK files. This .LNK files point out to a dropped copy of itself in the removable drive.

  SOLUTION

Minimum Scan Engine: 9.750
FIRST VSAPI PATTERN FILE: 11.500.05
FIRST VSAPI PATTERN DATE: 25 Feb 2015
VSAPI OPR PATTERN File: 11.501.00
VSAPI OPR PATTERN Date: 26 Feb 2015

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

Remove malware/grayware files dropped/downloaded by VBS_DUNIHI.TUOB. (Note: Please skip this step if the threats listed below have already been removed.)

Step 4

Scan your computer with your Trend Micro product and note files detected as VBS_DUNIHI.TUOB

Step 5

Restart in Safe Mode

[ Learn More ]

Step 6

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

Step 7

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 8

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