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Worm.VBS.DUNIHI.YYSYA

December 16, 2024
 Modified by: Paulo Samson
 ALIASES:

VBS.Dunihi (NORTON) , VBS/Dinihou-A (SOPHOS_LITE)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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.

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

  TECHNICAL DETAILS

File Size:

20,480 bytes

File Type:

VBS

Initial Samples Received Date:

09 Nov 2020

Payload:

Drops files, Connects to URLs/IPs, Steals information

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 copies of itself into the affected system and executes them:

  • %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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • "%System%\wscript.exe" //B "%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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Autostart Technique

This Worm adds the following registry entries to enable its automatic execution at every system startup:

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

HKEY_CURRENT_USER\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 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).)

Other System Modifications

This Worm 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:

  • {Removable Drive}:\{Malware Filename}.vbs
  • {Removable Drive}:\{Filename / Folder Name}.lnk

It sets the attributes of the following items to Hidden to trick the user into clicking the .LNK files:

  • {Removable Drive}:\{Filename / Folder Name}

Backdoor Routine

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

  • "execute" - Execute specified files
  • "update" - Update malware file and restart malware
  • "uninstall" - delete files drop by the malware, autorun registries and shortcut files on removable drives
  • "send" - Download and run a file from the C&C server
  • "site-send" - Download and run a file
  • "recv" - Send file to C&C Server
  • "enum-driver" - Send list of drives
  • "enumfaf" - Send list of files and folders
  • "enum-process" - Send list of processes
  • "cmd-shell" - Execute a command using Command Prompt with specified info
  • "delete" - Delete specified 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://tftp.{BLOCKED}tp.com:8088/is-ready

Information Theft

This Worm gathers the following data:

  • Computer Name
  • Username
  • Operating System Name
  • Volume Serial Number
  • Installed Antivirus Products

Other Details

This Worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\{Malware Filename}

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

16.354.05

FIRST VSAPI PATTERN DATE:

16 Nov 2020

VSAPI OPR PATTERN File:

16.355.00

VSAPI OPR PATTERN Date:

17 Nov 2020

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

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

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
  • {Removable Drive}:\{Malware Filename}.vbs
  • {Removable Drive}:\{Filename / Folder Name}.lnk

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.VBS.DUNIHI.YYSYA. 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

  1. Open a command prompt.
    • For Windows 7 users, click Start, enter CMD in the Find input field, and press Enter.
  2. In the CMD console, enter the following:

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

    Where:
    + Activates an attribute
    - Disables an attribute
    R Read-only file attribute
    A Archive file attribute
    S System file attribute
    H Hidden file attribute
    I Indexed file attribute without content
    [drive:][path][filename]
    Specifies one or more files in the current folder and all its subfolders
    /S Processes the corresponding files in the current folder and all its subfolders
    /D Process folders
    /L Act on the attributes of the symbolic link instrad of the target of the symbolic link
    Example:
    To make all files and folders (including subfolders visible in drive D:
    ATTRIB –H D:\* /S /D
  3. Repeat the step above for folders and files from other drives or directories.


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