BKDR_HORST.JW

Malware type: Backdoor

Aliases: No Alias Found

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 98, ME, NT, 2000, XP, Server 2003

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

Low

Description: 

This backdoor may be dropped by other malware.

It creates folders.

It registers itself as a system service to ensure its automatic execution at every system startup. It does this by creating registry keys/entries.

It drops component files.

It is capable of gathering and sending specific iinformation. It sends the gather data via HTTP Post to a certain remote server.

For additional information about this threat, see:

Description created: Apr. 20, 2010 2:30:07 AM GMT -0800


TECHNICAL DETAILS


Memory resident:  Yes

Size of malware: Varies

Initial samples received on: Feb 17, 2010

Related toTROJ_PIDIEF.PGT, TROJ_PIDIEF.PGU

Payload 1: Steals information

Details:

Arrival Details

This backdoor may be dropped by the following malware:

  • TROJ_PIDIEF.PGT
  • TROJ_PIDIEF.PGU

Installation

This backdoor creates the following folder(s):

  • %User Profile%\AppData
  • %User Profile%\AppData\Local
  • %User Profile%\AppData\Local\Driver
  • %User Profile%\AppData\Local\Windows

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

Autostart Techniques

It registers itself as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry key(s)/entry(ies):

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\
Installed Components\
{FB083534-2709-3378-0000-F0FCD03BA387}
IsInstalled = "1"
Locale = "en"
StubPath = "%User Profile%\AppData\Local\Windows\tlbsrch.exe"
Version = "3.1,1001"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\
Installed Components\
{FB083534-2709-3378-0001-F0FCD03BA387}
IsInstalled = "1"
Locale = "en"
StubPath = "%User Profile%\AppData\Local\Windows\tlbsrch.exe"
Version = "3.2,1004"

Backdoor Routine

It drops the non-malicious Microsoft file, %User Profile%\AppData\Local\Driver\detoured.dll, in order to successfully execute the following component:

  • %User Profile%\AppData\Local\Driver\acropdf32.dll

Once successfully running, this DLL connects to a predetermined remote site where it may receive malicious commands from a remote malicious user.

It requires other components to successfully exhibit the payload.

Dropping Routine

This backdoor drops the following component file(s):

  • %User Profile%\AppData\Local\Driver\acropdf32.dll - also detected as BKDR_HORST.JW
  • %User Profile%\AppData\Local\Driver\detoured.dll - non-malicious component
  • %User Profile%\AppData\Local\Windows\tlbsrch.exe - also detected as BKDR_HORST.JW
  • %User Temp%\wuaultup.exe - also detected as BKDR_HORST.JW

(Note: %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.)

Other Details

It is capable of injecting codes to legitimate Windows processes in order to stay memory resident.

If the affected system's operating system is Windows 98, it injects codes to mprexe.exe.

If the operating system is Windows XP, it injects codes to the following processes:

  • alg.exe
  • spoolsv.exe
  • wuauclt.exe

It is capable of gathering and sending the following information:

  • User information
  • CPU information
  • Operating system
  • Net Card information

It sends the gather data via HTTP Post to the following remote server:

    http://{BLOCKED}252.12/rbin/update.php

Affected Platforms

This backdoor runs on Windows 98, ME, NT, 2000, XP, and Server 2003.


Analysis By: Romeo dela Cruz

Revision History:

First pattern file version: 7.128.04
First pattern file release date: Apr 25, 2010

SOLUTION


Minimum scan engine version needed: 8.900

Pattern file needed: 7.347.00

Pattern release date: Jul 29, 2010


Important note: The "Minimum scan engine" refers to the earliest Trend Micro scan engine version guaranteed to detect this threat. However, Trend Micro strongly recommends that you update to the latest version in order to get comprehensive protection. Download the latest scan engine here.

Solution:

For Windows ME and XP users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

 Step 1: Remove malware files related to BKDR_HORST.JW  

    - No data found in "Related Malware" field. -

 Step 2:  Delete this registry key  [learn how]

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_LOCAL_MACHINE\SOFTWARE\Microsoft\
    Active Setup\Installed Components
    • {FB083534-2709-3378-0000-F0FCD03BA387}
    • {FB083534-2709-3378-0001-F0FCD03BA387}

 Step 3: Search and delete this folder  [learn how]

*Note: 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.

  • %User Profile%\AppData
  • %User Profile%\AppData\Local
  • %User Profile%\AppData\Local\Driver
  • %User Profile%\AppData\Local\Windows

 Step 4: Scan your computer with your Trend Micro product to delete files detected as BKDR_HORST.JW  

*Note: 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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