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X97M_LAROUX.AE

October 09, 2012
 Analysis by: Rhena Inocencio
 ALIASES:

Virus:X97M/Laroux.gen!A (Microsoft), X97M/Laroux (McAfee), X97M.Laroux.gen (Symantec), a variant of X97M/Escop.E.Gen virus (Nod32)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This file infector arrives by opening .XLS files which are infected by this malware. It drops the copies of itself into affected system. It infects certain files.

  TECHNICAL DETAILS

File Size:

188,928 bytes

File Type:

XLS

Initial Samples Received Date:

12 Sep 2012

Payload:

Creates files

Arrival Details

This malware arrives via the following means:

  • Opening .XLS files which are infected by this malware

NOTES:

This malware hooks the macro auto_open().

It checks if the following file exists:

  • %User Profile%\Application Data\Microsoft\Excel\XLSTART\StartUp.xls

If the file does not exist, it creates a copy of the active workbook in the said folder as StartUp.xls.

It infects Microsoft Office Excel files by creating a macro module named StartUp, which contains the malware codes.

This macro script intercepts the use of two function buttons in Microsoft Excel, namely the F8 and F11 buttons. Pressing these buttons allows the macro script to be executed.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.390.04

FIRST VSAPI PATTERN DATE:

12 Sep 2012

VSAPI OPR PATTERN File:

9.391.00

VSAPI OPR PATTERN Date:

13 Sep 2012

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Scan your computer with your Trend Micro product to clean files detected as X97M_LAROUX.AE. 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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