ALIASES:

Trojan:Win32/Startpage.MP (Microsoft); Downloader-CKO (McAfee); Suspicious.MH690 (Symantec); Trojan-Downloader.Win32.Agent.eckt (Kaspersky); Trojan-Downloader.Win32.Agent (Sunbelt); Gen:Variant.Graftor.2666 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 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.

  TECHNICAL DETAILS

File Size: 274,432 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 12 Jan 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 creates the following folders:

  • %Program Files%\Internet Explorer\MUI
  • %Program Files%\Thunder
  • %Program Files%\Thunder\ComDlls
  • %Program Files%\Thunder\ComDlls\1143

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

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main\Frist

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.msm4

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
msm4file

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
msm4file\DefaultIcon

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
msm4file\shell

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
msm4file\shell\open

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
msm4file\shell\open\
command

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
msm4file\shellex

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
msm4file\shellex\ContextMenuHandlers

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Direct3D\Drivers\SoftInfo

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Direct3D\Drivers\SoftInfo
FileName = "msm4"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Direct3D\Drivers\SoftInfo
GUIDTao = "{F46E512B-E2AC-4901-97C2-3A35910C0256}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Direct3D\Drivers\SoftInfo
IeToName = "cwugn"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Toolbar\WebBrowser
ITBar7Layout = "{random values}"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Toolbar\WebBrowser
ITBarLayout = "{random values}"

Dropping Routine

This Trojan drops the following files:

  • %Windows%\Downloaded Program Files\game.ico
  • %Windows%\Downloaded Program Files\mm.ico
  • %Windows%\Downloaded Program Files\movie.ico
  • %Windows%\Downloaded Program Files\taobao.ico
  • %System Root%\b.txt
  • %Program Files%\Internet Explorer\MUI\iexplore.exe
  • %Program Files%\Thunder\ComDlls\1143\taobao.ico
  • %Program Files%\Thunder\ComDlls\1143\game.ico
  • %Program Files%\Thunder\ComDlls\1143\movie.ico
  • %Program Files%\Thunder\ComDlls\1143\mm.ico
  • %Program Files%\Thunder\ComDlls\1143\bubhlq.exe
  • %System Root%\Documents and Settings\Administrator\Desktop\Internet Explorer.msm4
  • %System Root%\Documents and Settings\Administrator\Application Data\Microsoft\Internet Explorer\Quick Launch\Æô¶¯ Internet Explorer ä¯ÀÀÆ÷.msm4
  • %System Root%\Documents and Settings\Administrator\Start Menu\Internet Explorer.msm4
  • %System Root%\Documents and Settings\Administrator\Start Menu\³ÌÐò\Internet Explorer.msm4

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

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://www.{BLOCKED}r.com/down/new.htm

This report is generated via an automated analysis system.

  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.

  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Frist
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes
    • .msm4
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes
    • msm4file
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\msm4file
    • DefaultIcon
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\msm4file
    • shell
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\msm4file\shell
    • open
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\msm4file\shell\open
    • command
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\msm4file
    • shellex
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\msm4file\shellex
    • ContextMenuHandlers
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Direct3D\Drivers
    • SoftInfo

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\Direct3D\Drivers\SoftInfo
    • FileName="msm4"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Direct3D\Drivers\SoftInfo
    • GUIDTao="{F46E512B-E2AC-4901-97C2-3A35910C0256}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Direct3D\Drivers\SoftInfo
    • IeToName="cwugn"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Toolbar\WebBrowser
    • ITBar7Layout="{random values}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Toolbar\WebBrowser
    • ITBarLayout="{random values}"

Step 4

Search and delete these files

[ 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.
  • %Windows%\Downloaded Program Files\game.ico
  • %Windows%\Downloaded Program Files\mm.ico
  • %Windows%\Downloaded Program Files\movie.ico
  • %Windows%\Downloaded Program Files\taobao.ico
  • %System Root%\b.txt
  • %Program Files%\Internet Explorer\MUI\iexplore.exe
  • %Program Files%\Thunder\ComDlls\1143\taobao.ico
  • %Program Files%\Thunder\ComDlls\1143\game.ico
  • %Program Files%\Thunder\ComDlls\1143\movie.ico
  • %Program Files%\Thunder\ComDlls\1143\mm.ico
  • %Program Files%\Thunder\ComDlls\1143\bubhlq.exe
  • %System Root%\Documents and Settings\Administrator\Desktop\Internet Explorer.msm4
  • %System Root%\Documents and Settings\Administrator\Application Data\Microsoft\Internet Explorer\Quick Launch\Æô¶¯ Internet Explorer ä¯ÀÀÆ÷.msm4
  • %System Root%\Documents and Settings\Administrator\Start Menu\Internet Explorer.msm4
  • %System Root%\Documents and Settings\Administrator\Start Menu\³ÌÐò\Internet Explorer.msm4

Step 5

Search and delete these folders

[ 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%\Internet Explorer\MUI
  • %Program Files%\Thunder
  • %Program Files%\Thunder\ComDlls
  • %Program Files%\Thunder\ComDlls\1143

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAM_000197a.TOMA. 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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