Virus Profile: X97M/Laroux.a.gen

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Virus Profile information details
Risk Assessment: Home Low | Corporate Low
Date Discovered: 9/1/2004
Date Added: 9/1/2004
Origin: Unknown
Length: N/A
Type: Virus
Subtype: Generic
DAT Required: N/A
Removal Instructions


This is a virus detection. Viruses are programs that self-replicate recursively, meaning that infected systems spread the virus to other systems, which then propagate the virus further. While many viruses contain a destructive payload, it's quite common for viruses to do nothing more than spread from one system to another.


  • Drweb           -          XM.Laroux
  • Ikarus           -          Virus.MSExcel.Laroux.cs
  • Symantec    -          X97M.Laroux.gen
  • Kaspersky    -         Virus.MSExcel.Laroux.cs

Indication of Infection

Presence of above mentioned activities.

Methods of Infection

Opening infected workbook and allowing the macro code to run will copy a loader workbook named Book1.XLS to the XLSTART folder. Any workbook opened on this now infected system will become infected also.

Virus Characteristics

X97M/Laroux.a.gen is a macro virus that targets Excel workbooks. This virus does not have a destructive payload.

If macros are allowed to execute in MS Excel, the macro code will run when infected workbooks are opened.

Whenever a new workbook created or existing uninfected excel file opened, it inserts a sheet named ‘laroux’ with malicious macro-code in hidden mode, before the sheet1 in the opened workbook.  

The virus includes a dropper workbook named 'Book1.XLS' with hidden sheet ‘laroux’ stored in the XLStart folder of MS Excel.

Notes: XLStart folder refers to the folder from the MS-Excel application gets launched. Eg. C:\Documents and Settings\Administrator\Application Data\Microsoft\Excel\XLSTART


All Users :

Script,Batch,Macro and non memory-resident:
Use current engine and DAT files for detection and removal.

PE,Trojan,Internet Worm and memory resident :

Use specified engine and DAT files for detection. To remove, boot to MS-DOS mode or use a boot diskette and use the command line scanner:


Additional Windows ME/XP removal considerations

Users should not trust file icons, particularly when receiving files from others via P2P clients, IRC, email or other mediums where users can share files.

AVERT Recommended Updates :

* Office2000 Updates

* Malformed Word Document Could Enable Macro to Run Automatically (Information/Patch )

* scriptlet.typelib/Eyedog vulnerability patch

* Outlook as an email attachment security update

* Exchange 5.5 post SP3 Information Store Patch 5.5.2652.42 - this patch corrects detection issues with GroupShield

For a list of attachments blocked by the Outlook patch and a general FAQ, visit this link .
Additionally, Network Administrators can configure this update using an available tool - visit this link for more information .

It is very common for macro viruses to disable options within Office applications for example in Word, the macro protection warning commonly is disabled. After cleaning macro viruses, ensure that your previously set options are again enabled.


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