X2KM_TOXOCARA.A

November 10, 2017
 Analysis by: Christopher Daniel So
 ALIASES:

Trojan.Mdropper (Symantec), PowerShell/Agent.N trojan (ESET), X97M/Powershell.gen (F-Prot), VBA/PowerShell.A376!tr (Fortinet)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • 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:

56,832 bytes

File Type:

XLS

Memory Resident:

Yes

Initial Samples Received Date:

08 Nov 2017

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 creates the following folders:

  • %System Root%:\Users\Public\Libraries

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

Dropping Routine

This Trojan drops the following files:

  • %System Root%:\Users\Public\Libraries\test5.vbs
  • %System Root%:\Users\Public\Libraries\test5.txt - detected by Trend Micro as BKDR_TOXOCARA.A

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

NOTES:
It creates a Scheduled Task named Office_Update that executes the dropped file %System Root%:\Users\Public\Libraries\test5.vbs. It then triggers the Scheduled Task, thereby immediately executing the dropped file.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.770.07

FIRST VSAPI PATTERN DATE:

10 Nov 2017

VSAPI OPR PATTERN File:

13.771.00

VSAPI OPR PATTERN Date:

10 Nov 2017

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

Remove the malware/grayware file dropped/downloaded by X2KM_TOXOCARA.A. (Note: Please skip this step if the threat(s) listed below have already been removed.)

Step 3

To delete the added Scheduled Task:

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Click on Start>Programs>Accessories>System Tools>Scheduled Tasks
  2. Double-click on a job file.
  3. Check if the malware path and file name is in the Run: box.
  4. If it does, delete the job file.
  5. Repeat step 2-4 for the remaining job files.

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

  1. Open the Windows Task Scheduler. To do this:
    • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
    • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower-left corner of the screen, click Run, type taskschd.msc, then press Enter.
  2. In the left panel, click Task Scheduler Library.
  3. In the upper-middle panel, select a Task.
  4. Check if the selected task starts the malware automatically. To do this, check the value in the Details column under the Actions tab in the lower-middle panel.
  5. If the malware path and file name is found, press DELETE and click Yes to delete the task.
  6. Repeat steps 3-5 for the remaining tasks.

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.
  • %System Root%:\Users\Public\Libraries

Step 5

Scan your computer with your Trend Micro product to delete files detected as X2KM_TOXOCARA.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.

NOTES:
Before deleting the Scheduled Task Office_Update, close all instances of Microsoft Excel.


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