VBS_JENXCUS.MJN

 Analysis by: Donald Adrian Castillo

 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:

Via physical/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 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 retrieves specific information from the affected system.

  TECHNICAL DETAILS

File Size:

70, 619 bytes

File Type:

VBS

Memory Resident:

Yes

Initial Samples Received Date:

27 Jun 2015

Payload:

Connects to URLs/IPs, Collects system 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:

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

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.. %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.)

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 %Appication Data%\{Malware Filename}.vbs""

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

It drops the following file(s) in the Windows 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 keys 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

Backdoor Routine

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

  • excecute - executes file
  • update - update and restart itself
  • uninstall - uninstall itself
  • send - download and run a file from C&C server
  • site-send - download and run a file
  • recv - send a file to C&C server
  • enum-driver - send list of drives
  • enum-faf - enumerate folders and files contained in a directory
  • enum-process - list running processes, its corresponding process ID and its location
  • cmd-shell - perform remote shell
  • delete - delete files and folders
  • exit-process - terminates process
  • sleep - sleeps process

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

  • http://mse3.{BLOCKED}ties.com:1003/is-ready
  • http://mse3.{BLOCKED}ties.com:1003/is-sending
  • http://mse3.{BLOCKED}ties.com:1003/is-recving

Information Theft

This worm retrieves the following information from the affected system:

  • Volume serial number of logical drives
  • Antivirus products installed
  • Current user name
  • Computer name
  • OS version

NOTES:

This malware creates .LNK files whose file names correspond to the files and folders found in the root directory of removable drives. When the .LNK files are executed, the dropped copy of the malware on the drive and the file/folder it links to are both executed.

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.754.08

FIRST VSAPI PATTERN DATE:

26 Jun 2015

VSAPI OPR PATTERN File:

11.755.00

VSAPI OPR PATTERN Date:

26 Jun 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

Scan your computer with your Trend Micro product and note files detected as VBS_JENXCUS.MJN

Step 4

Restart in Safe Mode

[ Learn More ]

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

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

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 %Appication Data%\{Malware Filename}.vbs""
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • {Malware Filename} = "wscript.exe //B %Appication Data%\{Malware Filename}.vbs""

Step 7

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.
  • %Application Data%\{Malware Filename}.vbs
  • %User Startup%\{Malware Filename}.vbs
  • {Removable Drive Letter}:\{Malware Filename}.vbs
  • {Removable Drive Letter}:\{Filename or Folder name}.LNK

Step 8

  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 9

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