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VBS_STARTER.AUSE

November 10, 2017
 Analysis by: Nikko Tamana
 ALIASES:

VBS/Kryptik.HJ!tr (Fortinet), Trojan.VBS.Crypt (Ikarus), Worm:VBS/Dinoh.A (Microsoft), VBS/Kryptik.HJ trojan (NOD32)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • 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.

It uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

  TECHNICAL DETAILS

File Type:

VBS

Memory Resident:

No

Initial Samples Received Date:

09 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 drops the following copies of itself into the affected system:

  • %Application Data%\MicrosoftDirectX11

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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 uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

Autostart Technique

The scheduled task executes the malware every:

  • minute

NOTES:
It creates the scheduled task MicrosoftDirectX11 to execute the dropped copy of itself.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.770.03

FIRST VSAPI PATTERN DATE:

09 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

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 the Scheduled Tasks added by this malware/grayware

[ Learn More ]

To delete the added Scheduled Task file:

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

  1. Open the Windows Scheduled Tasks. To do this, click Start>Programs>Accessories>System Tools>Scheduled Tasks.
  2. Double-click on a .JOB file.
  3. Check if the malware path and file name exists in the .JOB file. To do this, check the value in the Run field.
  4. If found, select the .JOB file then press SHIFT+DELETE to permanently delete the file.
  5. Repeat the steps above 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 of the Task Scheduler Window, click Task Scheduler Library.
  3. In the upper-middle panel, click a Task.
  4. In the lower middle panel, click the Actions tab
  5. Check if the malware path and file name exists in the task. To do this, check the value in the Details column under the Actions tab.
  6. If found, select the task and press DELETE and click Yes to delete the task.
  7. Repeat the steps above for the remaining tasks.

Step 4

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