Analysis by: Homer Pacag
ALIASES:

Worm:VBS/Jenxcus.BR(Microsoft); Backdoor.Ratenjay.C(Symantec)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware, Downloaded from the Internet

This malware is involved in the targeted attack incident that shut down a global French-language television network on April 2015. Users affected by this malware may find the security of their systems compromised.

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 drops copies of itself in all removable drives.

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.

  TECHNICAL DETAILS

File Size: 8,033 bytes
File Type: VBS
Memory Resident: Yes
Payload: Connects to URLs/IPs, Drops files, Compromises system security

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:

  • %User Temp%\{Malware name}.vbs
  • %User Startup%\SecurityNajaf.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.. %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 creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKCU\Software\Microsoft\
Windows\CurrentVersion\Run
SecurityNajaf = wscript.exe //B "SecurityNajaf.vbs"

HKLM\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SecurityNajaf = wscript.exe //B "SecurityNajaf.vbs"

Propagation

This worm drops copies of itself in all removable drives.

Backdoor Routine

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

  • uninstall - remove dropped files and created registries
  • RE - reloads script
  • download - downloads and save fie from url
  • update - overwrite script
  • execute -execute file
  • cmd - shell command
  • Attack - continuous ping
  • ourl - access a url
  • close - terminate script
  • restart - forced restart of machine command
  • shutdown - forced shutdown of machine command
  • logoff - forced logoff of machine command

Information Theft

This worm gathers the following data:

  • HDD Serial Numbers
  • Operating System
  • Computer Name
  • Username
  • Installed AV Products
  • Present USB Drives

NOTES:

It connects to a C&C server hardcoded in its code to send and receive commands from a remote malicious user.

  SOLUTION

Minimum Scan Engine: 9.750
FIRST VSAPI PATTERN FILE: 11.503.00
FIRST VSAPI PATTERN DATE: 26 Feb 2015
VSAPI OPR PATTERN File: 11.504.00
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

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
    • SecurityNajaf = wscript.exe //B "SecurityNajaf.vbs"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • SecurityNajaf = wscript.exe //B "SecurityNajaf.vbs"

Step 5

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.
  • %User Temp%\{Malware name}.vbs
  • %User Startup%\SecurityNajaf.vbs

Step 6

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