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Virus.X97M.LAROUX.A

September 19, 2023
 Analysis by: John Rainier Navato
 ALIASES:

Virus:X97M/Laroux.HT (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Virus

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


This Virus arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It does not have any propagation routine.

It does not have any backdoor routine.

  TECHNICAL DETAILS

File Size:

349,696 bytes

File Type:

XLS, Other

Memory Resident:

No

Initial Samples Received Date:

11 Sep 2023

Arrival Details

This Virus arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Propagation

This Virus does not have any propagation routine.

Backdoor Routine

This Virus does not have any backdoor routine.

Rootkit Capabilities

This Virus does not have rootkit capabilities.

Other Details

This Virus does the following:

  • It will remain active every time Excel is launched, infecting any new workbooks created and previously saved workbooks when they are opened.
  • It checks for a file named "PERSONAL.XLS" in the Excel startup path and if the currently active workbook contains any VBA modules.
    • If PERSONAL.XLS exists and the currently active workbook does not contain any VBA modules:
      • It copies a sheet named "laroux" from "PERSONAL.XLS" and paste it as the first sheet in the currently active Excel workbook.
      • It sets the copied sheet to hidden.
      • It assigns a macro from "PERSONAL.XLS" in the currently active Excel workbook for persistence
    • If PERSONAL.XLS doesn't exist and the currently active workbook contains any VBA modules:
      • It unhides a sheet named "laroux" in the currently active workbook
      • It copies the "laroux" sheet into a new workbook.
      • It sets the copied sheet to hidden.
      • It sets the following file attributes to null:
        • Title
        • Author
        • Subject
        • Keywords
        • Comments
      • It saves the new workbook as:
        • %Application Data%\Microsoft\Excel\XLSTART\PERSONAL.XLS
      • It assigns a macro from "PERSONAL.XLS" in the currently active Excel workbook for persistence

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

NOTES:

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.696.03

FIRST VSAPI PATTERN DATE:

14 Sep 2023

VSAPI OPR PATTERN File:

18.697.00

VSAPI OPR PATTERN Date:

15 Sep 2023

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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.  
  • %Application Data%\Microsoft\Excel\XLSTART\PERSONAL.XLS

Step 4

Scan your computer with your Trend Micro product to delete files detected as Virus.X97M.LAROUX.A. 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 the following Trend Micro Support pages for more information:


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