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WORM_NECAST.SM23

February 26, 2016
 Analysis by: Homer Pacag
 ALIASES:

Worm:MSIL/Necast.F (Microsoft); MSIL/Agent.QBS!tr (Fortinet)

 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

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.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE

Memory Resident:

No

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 files:

  • %Windows%\system\wsystem.vx

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

It drops the following copies of itself into the affected system:

  • %Windows%\system\svchost..exe

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

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:

  • {Drive Letter}:\movies.exe

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

11.442.08

FIRST VSAPI PATTERN DATE:

28 Jan 2015

VSAPI OPR PATTERN File:

11.443.00

VSAPI OPR PATTERN Date:

28 Jan 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

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.  
  • %Windows%\system\wsystem.vx
  • %Windows%\system\svchost..exe
  • %User Startup%\svchost..exe
  • {Drive Letter}:\movies.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as WORM_NECAST.SM23. 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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