Analysis by: Sabrina Lei Sioting
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • 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.

  TECHNICAL DETAILS

File Size: 16,382 bytes
File Type: Other
Memory Resident: No
Initial Samples Received Date: 19 Oct 2011

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:

  • %Windows%\DivX.fin
  • %Program Files%\AutoCAD\Fonts\isohztxt.shx

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

Other System Modifications

This Trojan adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\FileKen\
settings

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Setup\
BEI_ZHU

Other Details

This Trojan connects to the following possibly malicious URL:

  • www.{BLOCKED}s.com

NOTES:
It enables the Windows Scripting Host by creating the following registry entry:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Script Host\Settings
Enabled = 1

It deletes the following files, if found:
  • isohztxt.shx
  • isomianyi.shx

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.508.02
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

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

 
  • In HKEY_CURRENT_USER\Software\FileKen
    • settings
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Setup
    • BEI_ZHU

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Script Host\Settings
    • Enabled = 1

Step 4

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

Step 5

Restore these deleted files from backup

*Note: Only Microsoft-related keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

isohztxt.shx
isomianyi.shx


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