Analysis by: Jaime Benigno Reyes
ALIASES:

Troj/Agent-AAZR (Sophos), Trojan horse Downloader.Generic13.ANHN (AVG), W32/Agent.RFK!tr.dldr (Fortinet), Trojan.Win32.Spy (Ikarus)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

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

It executes commands from a remote malicious user, effectively compromising the affected system.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 25,088 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 04 Apr 2013
Payload: Compromises system security

Arrival Details

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

  • TROJ_MSDOWNL.A

Infection Points

This Backdoor arrives as a file downloaded from the following URLs:

  • http://{BLOCKED}ecure.com/update/winword.pkg

Installation

This Backdoor drops the following copies of itself into the affected system and executes them:

  • %ProgramData%\Google2\GoogleUpdate.exe (Windows Vista and higher versions)
  • %System Root%\ProgramData\Google2\GoogleUpdate.exe (Versions lower than Windows Vista)

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData in Windows Vista, 7, and 8.. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It creates the following folders:

  • %ProgramData%\Google2 (Windows Vista and higher versions)
  • %System Root%\ProgramData (Versions lower than Windows Vista)
  • %System Root%\ProgramData\Google2 (Versions lower than Windows Vista)

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData in Windows Vista, 7, and 8.. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • MM-Core-Running

Autostart Technique

This Backdoor drops the following shortcut pointing to its copy in the User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\GoogleUpdate.lnk

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows XP, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

  • Download a file from C&C server and save it as %User Temp%\java.{random} and execute it
  • Read a code from C&C server and execute it as a separate thread
  • Uninstall itself

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.)

It posts the following information to its command and control (C&C) server:

  • Operating system version
  • Computer Name
  • User Name
  • List of currently running processes
  • Full IP configuration information
  • List of files and subdirectories in drives C to H

Other Details

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

  • http://symbisecure.com/adserv/get.php

NOTES:

This backdoor connects to the following URL to read a part of its code and execute it in memory:

  • http://{BLOCKED}r.no-ip.org/adserv/logo.jpg

It only connects to the mentioned URL when it detects three mouse clicks or more.

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.834.07
FIRST VSAPI PATTERN DATE: 04 Apr 2013
VSAPI OPR PATTERN File: 9.835.00
VSAPI OPR PATTERN Date: 04 Apr 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Remove malware/grayware files that dropped/downloaded BKDR_BANECHANT.A. (Note: Please skip this step if the threats listed below have already been removed.)

     
    • TROJ_MSDOWNL.A

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete this file

[ Learn More ]
There may be some 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.
  • %User Startup%\GoogleUpdate.lnk
  • %User Temp%\java.{random}

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.
  • %ProgramData%\Google2 (Windows Vista and higher versions)
  • %System Root%\ProgramData\Google2 (Versions lower than Windows Vista)

Step 6

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