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X97M_OLEMAL.A

March 20, 2017
 Analysis by: Michael Cabel
 Modified by: Joselyn Canuela
 ALIASES:

Virus:X97M/Mailcab.A (Microsoft), Trojan.VBS.Agent (Ikarus), Virus.MSExcel.Agent.f (Kaspersky), X97M/Dropper.Agent (AVG)

 PLATFORM:

Windows

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

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Spammed via email


This file infector arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

  TECHNICAL DETAILS

File Size:

2,927,616 bytes

File Type:

XLS

Memory Resident:

No

Initial Samples Received Date:

17 Mar 2017

Arrival Details

This file infector arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

This file infector adds the following folders:

  • D:\Collected_Address
  • E:\KK
  • E:\SORCE

It drops a copy of itself in the following folders using different file names:

  • %User Profile%\Application Data\Microsoft\Excel\XLSTART\k4.xls

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It drops and executes the following files:

  • E:\KK\{Malware filename}_clear.vbs - script helps in creating the email messages by sending keystroke commands to Microsoft Outlook
  • E:\KK\{Malware filename}_Search.vbs - script helps in gathering the email messages
  • E:\SORCE\{Malware filename}_Key.vbs - script helps in sending the email messages

It drops the following non-malicious file:

  • D:\Collected_Address\frag1.txt
  • D:\Collected_Address\frag2.txt
  • D:\Collected_Address\log.txt

Other System Modifications

This file infector adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Office\{Application Version}\Excel\
Security
AccessVBOM = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Office\{Application Version}\Excel\
Security
Level = "1"

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Office\{Application Version}\Excel\
Security
Level = "1"

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Office\{Application Version}\Excel\
Security
AccessVBOM = "1"

Other Details

This file infector does the following:

  • This file infector copies itself into all open Microsoft Excel files as a macro module with the name "ToDOLE".
  • It performs its spamming routine if the time is between 10:00:00-11:00:00 and 14:00:00-15:00:00.

NOTES:

It gathers target email addresses from the Inbox folder of the mailbox.

It uses the MAPI to send email messages that contains the following information:

  • To: {email address}
  • Subject: {Malware filename}
  • Body:

    Dear all,

    {Malware filename}

    FYI

  • Attachment: {Malware filename}.cab

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

10.686.04

FIRST VSAPI PATTERN DATE:

25 Mar 2014

VSAPI OPR PATTERN File:

10.687.00

VSAPI OPR PATTERN Date:

26 Mar 2014

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

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\{Application Version}\Excel\Security
    • AccessVBOM = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\{Application Version}\Excel\Security
    • Level = "1"
  • In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\{Application Version}\Excel\Security
    • AccessVBOM = "1"
  • In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\{Application Version}\Excel\Security
    • Level = "1"

Step 4

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • D:\Collected_Address
  • E:\KK
  • E:\SORCE

Step 5

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.
  • User Profile%\Application Data\Microsoft\Excel\XLSTART\k4.xls

Step 6

Scan your computer with your Trend Micro product to delete files detected as X97M_OLEMAL.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 this Knowledge Base page for more information.


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