Analysis by: Mark Joseph Manahan
ALIASES:

W32/Palevo-BZ (Sophos) ,Worm/Generic2.AXRQ (AVG) ,W32/MSIL_Agent.K.gen!Eldorado (generic, not disinfectable) (Fprot) ,Worm.Win32.Msil (Ikarus) ,Worm.MSIL.Agent.js (Kaspersky) ,Worm:MSIL/Necast.F (Microsoft) ,Generic Malware.og!ats (McAfee) ,MSIL/Agent.AY worm (Eset) ,Infostealer (Symantec) ,Trj/Sinowal.WWG (Panda) ,Trojan.Win32.Generic!BT (Sunbelt)

 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: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Propagates via removable drives, Dropped by other malware, Downloaded from the Internet

This worm arrives by connecting affected removable drives to a system. 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 retrieves specific information from the affected system.

  TECHNICAL DETAILS

File Size: 102,400 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 03 Mar 2014
Payload: Steals information

Arrival Details

This worm arrives by connecting affected removable drives to a system.

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 and executes them:

  • %Windows%\system\svchost..exe (For Windows XP and prior)
  • %User Profile%\Documents\suchost..exe (For Windows Vista and later)

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Autostart Technique

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

  • %User Startup%\svchost..exe

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Propagation

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

  • movies.exe

Information Theft

This worm retrieves the following information from the affected system:

  • Filenames of all .JPG files found in local drives
  • Filenames of all .XLSX files found in local drives
  • Filenames of all .DOCX files found in local drives

Stolen Information

The stolen information is saved in the following file:

  • %System Root%\Users\Public\Documents\wsystem.vx (For Windows Vista and later)
  • %Windows%\system\wsystem.vx (For Windows XP and prior)

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It sends the data it gathers to the following email addresses via SMTP:

  • {BLOCKED}iler411@gmail.com

NOTES:

It connects to the following SMTP server to send the stolen information:

  • smtp.gmail.com - Port: 587

It uses the following email credentials to log in the SMTP server:

  • user: {BLOCKED}iler411@gmail.com
  • password: benhurdavies20

The email it send may contain the following information:

  • From: {BLOCKED}iler411@gmail.com
  • To: {BLOCKED}iler411@gmail.com
  • Subject: {Username of Infected Machine}
  • Attachment: wsystem.vx
  • body: mac address : {mac address of infected machine}
  • file path : {target drive in stealing information}

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.640.03
FIRST VSAPI PATTERN DATE: 03 Mar 2014

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

Identify and terminate files detected as WORM_NECAST.K

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

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. %System Root%\Users\Public\Documents\wsystem.vx
%Windows%\system\wsystem.vx

Step 4

Scan your computer with your Trend Micro product to delete files detected as WORM_NECAST.K. 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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