Analysis by: Sabrina Lei Sioting
ALIASES:

Trojan:JS/Startpage.Y (Microsoft), PAK:UPX, ARC:Embedded, [script.au3]:Trojan.Win32.Autoit.aen, [script.au3]:Trojan.Win32.Autoit.aen, [nlse.cs]:Trojan.JS.StartPage.bd (Kaspersky), StartPage-MJ (McAfee), Trojan.JS.StartPage (Ikarus),

 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 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: 290,661 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 28 Jul 2012

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 files:

  • %System Root%\Documents and Settings\All Users\Desktop\Internet Explorer.lnk
  • %Program Files%\Thunder\Wrper.syc

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

It creates the following folders:

  • %Program Files%\Thunder

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

Other System Modifications

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

HKEY_CLASSES_ROOT\lnkfile\shell\
open\command
{default} = ""%System%\WScript.exe" "%Program Files%\Thunder\Wrper.syc" "%1" %*"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
lnkfile\shell\open\
command
{default} = ""%System%\WScript.exe" "%Program Files%\Thunder\Wrper.syc" "%1" %*"

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

HKEY_CLASSES_ROOT\lnkfile\shell

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
lnkfile\shell

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://www.{BLOCKED}0.com/?g3
  • http://www.{BLOCKED}3.com/?tn=02023048_25_hao_pg

  SOLUTION

Minimum Scan Engine: 9.200

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_CLASSES_ROOT\lnkfile
    • shell
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\lnkfile
    • shell

Step 3

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.
  • %Program Files%\Thunder

Step 4

Search and delete this file

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.
  • %System Root%\Documents and Settings\All Users\Desktop\Internet Explorer.lnk

Step 5

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