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VBS_DROPPER.WYAA

January 08, 2015
 Analysis by: Rika Joi Gregorio
 ALIASES:

Virus.ASP.Backdoor(Ikarus), VBS/Kryptik.AA trojan(Nod32)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware

This Trojan may be dropped by other malware.

  TECHNICAL DETAILS

File Size:

1,608,534 bytes

File Type:

VBS

Memory Resident:

Yes

Initial Samples Received Date:

06 Jan 2015

Payload:

Drops files, Executes files

Arrival Details

This Trojan may be dropped by other malware.

Installation

This Trojan drops the following non-malicious file:

  • {malware path}\NVBCK.exe - copy of autoit.exe

NOTES:

This malware will check if the dropped file {malware path}:\NVBCK.exe is currently running in the system.

If so, it will sleep for a second until the file is not currently running in the system. If {malware path}:\NVBCK.exe is not running, it will just delete the said file.

This trojan requires the existence of the following file to perform its intended routine: {malware path}\IKWWK

It will then execute the said component file using {malware path}\NVBCK.exe.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.394.03

FIRST VSAPI PATTERN DATE:

06 Jan 2015

VSAPI OPR PATTERN File:

11.395.00

VSAPI OPR PATTERN Date:

07 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

Scan your computer with your Trend Micro product and note files detected as VBS_DROPPER.WYAA

Step 4

Terminate a malware/grayware process

[ Learn More ]

*Note: If the detected process is not displayed in theWindows Task Manager, continue doing the next steps.

    DATA_GENERIC
  • Select the process then press the End Process button.
  • To check if the malware/grayware process/es has/have been terminated, close Windows Task Manager then open it again.
  • Close Windows Task Manager.

    • Step 5

    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.  
    • {malware path}\IKWWK
    • {malware path}\NVBCK.exe

    Step 6

    Scan your computer with your Trend Micro product to delete files detected as VBS_DROPPER.WYAA. 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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