VBS_OLEAR.C

 Analysis by: Jaime Benigno Reyes

 ALIASES:

VirTool:VBS/Obfuscator.H, Exploit:VBS/CVE-2014-6332 (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • 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 may be hosted on a website and run when a user accesses the said website.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

15,338 bytes

File Type:

Script

Initial Samples Received Date:

20 Mar 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.

It may be hosted on a website and run when a user accesses the said website.

Installation

This Trojan drops the following component file(s):

  • %User Temp%\Uninstall.Vbs - detected as HKTL_DLOADER.C

(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.)

Dropping Routine

This Trojan takes advantage of the following software vulnerabilities to drop malicious files:

Download Routine

This Trojan connects to the following URL(s) to download its component file(s):

  • http://{BLOCKED}eong.com/files/oms.exe

It saves the files it downloads using the following names:

  • %System Root%\rundll32.exe - detected as TROJ_TALOC.NSW

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

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

Other Details

This Trojan does the following:

  • It uses the hacking tool Uninstall.Vbs to download and execute the malicious file by starting the following process with parameters:
  • cscript.exe %User Temp%\Uninstall.Vbs {target URL} {destination file}

(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.)

NOTES:

It does not have rootkit capabilities.

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.558.05

FIRST VSAPI PATTERN DATE:

24 Mar 2015

VSAPI OPR PATTERN File:

11.559.00

VSAPI OPR PATTERN Date:

25 Mar 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

Remove malware/grayware files dropped/downloaded by VBS_OLEAR.C. (Note: Please skip this step if the threats listed below have already been removed.)

    • HKTL_DLOADER.C
    • TROJ_TALOC.NSW

Step 4

Close all opened browser windows

Step 5

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

Step 6

Download and apply these security patches Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.  


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