Analysis by: Sabrina Lei Sioting
 Modified by: Abraham Latimer Camba
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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

  TECHNICAL DETAILS

File Size: 11,717 bytes
File Type: VBS
Initial Samples Received Date: 19 Oct 2011

Arrival Details

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

NOTES:

It accesses the following URL:

  • http://{random string 1}/ab/{random string 2}?do_check=on

It executes the following command line:

  • "{random string 3}" "{returned string from accessing the URL}"

{random string 1} is read from the following registry entry:

HKCU\SOFTWARE\Microsoft\Impthon
Master

{random string 2} is read from the following registry entry:

HKCU\SOFTWARE\Microsoft\Impthon
ChannelHash

{random string 3} is read from the following registry entry:

HKCU\SOFTWARE\Microsoft\Impthon
Kernel

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.508.05
FIRST VSAPI PATTERN DATE: 19 Oct 2011
VSAPI OPR PATTERN File: 8.509.00
VSAPI OPR PATTERN Date: 20 Oct 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

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