Analysis by: Jasen Sumalapao
ALIASES:

Trojan.Win32.Generic!BT (Sunbelt), is suspected of Trojan.Downloader.gen.h (VBA32), Mal/Behav-116 (Sophos)

 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 may be downloaded by other malware/grayware/spyware from remote sites. It arrives as a component bundled with malware/grayware packages. It may be dropped by other malware.

It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size: Varies
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 06 Aug 2012

Arrival Details

This Trojan may be downloaded by other malware/grayware/spyware from remote sites.

It arrives as a component bundled with malware/grayware packages.

It may be dropped by the following malware:

  • TROJ_DROPPER.WSD

Installation

This Trojan drops the following component file(s):

  • {Malware Path}\ker.dll
  • %Program Files%\WindowsZip\temp\Update\window.exe
  • %Program Files%\WindowsZip\temp\0.txt
  • %User Temp%\wuauclt.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

It creates the following folders:

  • %Program Files%\WindowsZip\temp\Update

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

Autostart Technique

This Trojan modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
User Shell Folders
Common Startup = %Program Files%\WindowsZip\temp\Update

(Note: The default value data of the said registry entry is %ALLUSERSPROFILE%\Start Menu\Programs\Startup.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
load = %User Temp%\wuauclt.exe

(Note: The default value data of the said registry entry is "".)

Backdoor Routine

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

  • http://{BLOCKED}va2018.narod2.ru
  • http://{BLOCKED}z.yandex.ru

Information Theft

This Trojan sends the gathered information to the following site/s using credentials from its configuration file:

  • http://www.{BLOCKED}hooservice.com/cgi-edk/tdw.cgi

  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

Remove the malware/grayware file that dropped/downloaded TROJ_RUGENT.A

    • TROJ_DROPPER.WSD

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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%\WindowsZip

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.
  • {Malware Path}\ker.dll

Step 6

Restore this modified 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\CurrentVersion\Explorer\User Shell Folders
    • From: Common Startup = "%Program Files%\WindowsZip\temp\Update"
      To: Common Startup = "%ALLUSERSPROFILE%\Start Menu\Programs\Startup"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
    • From: load = "%User Temp%\wuauclt.exe"
      To: load = ""

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_RUGENT.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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