Analysis by: Joseph Obed
ALIASES:

Backdoor:Win32/Morix.B (Microsoft)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size: 200,837 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 01 Mar 2012

Installation

This backdoor drops the following files:

  • %Program Files%\Windows Media Player\wupdmgr32.dll
  • %Windows%\ThankU.txt

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

Autostart Technique

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

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wind0ws\Parameters
ServiceDll = "%Program Files%\Windows Media Player\wupdmgr32.dll"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wind0ws

HKEY_LOCAL_MACHINE\SOFTWARE\ThankU

Backdoor Routine

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

  • http://{BLOCKED}n.3322.org

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.808.06
FIRST VSAPI PATTERN DATE: 01 Mar 2012
VSAPI OPR PATTERN File: 8.809.00
VSAPI OPR PATTERN Date: 01 Mar 2012

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

Restart in Safe Mode

[ Learn More ]

Step 3

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.
  • %Program Files%\Windows Media Player\wupdmgr32.dll
  • %Windows%\ThankU.txt

Step 4

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_LOCAL_MACHINE\SYSTEM\ControlSet001\Services
    • wind0ws
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • ThankU

Step 5

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