X2KM_BARTALEX.CVB

September 21, 2015
 Analysis by: Mar Philip Elaurza
 ALIASES:

W97M.Downloader (Symantec), TrojanDownloader:O97M/Bartallex (Microsoft), X97M/Downloader.q (McAfee), Trojan-Downloader.MSExcel.Agent.al (Kaspersky), W97m.Downloader.UI (BitDefender)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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

  TECHNICAL DETAILS

File Size:

68,608 bytes

File Type:

XLS

Memory Resident:

Yes

Initial Samples Received Date:

18 Sep 2015

Arrival Details

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

Installation

This Trojan drops the following files:

  • %User Temp%\{5-digit-random filename}.vbs
  • %User Temp%\{5-digit-random filename}.ps1 -> will only be dropped for Windows Vista and above

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops and executes the following files:

  • %User Temp%\{5-digit-random filename}.bat

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}c.su/5751812.jpg - downloaded for Windows XP, 2000, and Server 2003
  • http://{BLOCKED}c.su/5757956.jpg - downloaded for Windows Vista and above

It connects to the following URL(s) to download its configuration file:

  • http://{BLOCKED}dquarters.com/wp-content/plugins/wordpress-importer/78672738612836.txt
  • http://{BLOCKED}dquarters.com/wp-content/plugins/wordpress-importer/papa.txt
  • http://{BLOCKED}ada.com/wp-content/plugins/checkout-bluepay/78672738612836.txt
  • http://{BLOCKED}ada.com/wp-content/plugins/checkout-bluepay/papa.txt

It saves the files it downloads using the following names:

  • %User Temp%\8.exe

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.788.07

FIRST VSAPI PATTERN DATE:

13 Jul 2015

VSAPI OPR PATTERN File:

11.789.00

VSAPI OPR PATTERN Date:

14 Jul 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 to clean files detected as X2KM_BARTALEX.CVB. 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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