Analysis by: MarfelTi

 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 may be downloaded by other malware/grayware from remote sites. However, as of this writing, the said sites are inaccessible.

It connects to certain websites to send and receive information. It restarts the affected system.

  TECHNICAL DETAILS

File Size: 663,040 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 21 Jun 2011
Payload: Sends and receives information

Arrival Details

This Trojan may be downloaded by the following malware/grayware from remote sites:

  • TROJ_INJECTOR.VI

It may be unknowingly downloaded by a user while visiting the following malicious websites:

  • http://{BLOCKED}dexchange2011.ru/abs.exe

However, as of this writing, the said sites are inaccessible.

Installation

This Trojan drops the following non-malicious files:

  • %Application Data%\ct_start
  • %Application Data%\1.gif

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

It drops the following copies of itself into the affected system:

  • %Application Data%\gog.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

It injects itself into the following processes as part of its memory residency routine:

  • csrss.exe
  • lsass.exe
  • explorer.exe

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\SOFTWARE\MICROSOFT\
WINDOWS NT\CURRENTVERSION\Winlogon
Shell = "%Application Data%\gog.exe"

Other Details

This Trojan connects to the following website to send and receive information:

  • http://{BLOCKED}.{BLOCKED}.210.88/inst_global.php?id=abs_03

It restarts the affected system.

  SOLUTION

Minimum Scan Engine: 8.900

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

Remove malware files dropped/downloaded by TROJ_CTGOG.VI

    TROJ_INJECTOR.VI

Step 3

Identify and terminate files detected as TROJ_CTGOG.VI

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

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_CURRENT_USER\SOFTWARE\MICROSOFT\WINDOWS NT\CURRENTVERSION\Winlogon
    • Shell = "%Application Data%\gog.exe"

Step 5

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. %Application Data%\ct_start
%Application Data%\1.gif

Step 6

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