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BKDR_APTDOOR.A

October 09, 2012
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW


This backdoor is capable of executing certain commands.

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

296,448 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

03 Feb 2012

Payload:

Steals information

Arrival Details

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

This backdoor drops the following files:

  • %User Profile%\tmp\msacm32.dll - log file
  • %User Temp%\chave.reg - component for creating auto-start registry
  • %User Temp%\prap.bat - batch file for installing malware components

(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.. %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 drops the following copies of itself into the affected system:

  • %User Profile%\tmp\hkcmd.exe

(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.)

It creates the following folders:

  • %User Profile%\tmp

(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 Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
igfhelp = "%User Profile%\tmp\hkcmd.exe"

Backdoor Routine

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

  • {BLOCKED}8.{BLOCKED}9.44.103
  • {BLOCKED}8.{BLOCKED}9.44.249
  • {BLOCKED}8.{BLOCKED}9.45.125
  • {BLOCKED}8.{BLOCKED}9.45.227
  • {BLOCKED}8.{BLOCKED}9.45.73
  • {BLOCKED}b2.{BLOCKED}site.org
  • {BLOCKED}b3.{BLOCKED}one.org

NOTES:

It is capable of executing the following commands:

  • Set/Change the IP address where it communicates with
  • Test the connection with the new IP/C&C server
  • Configure the time interval where the bot reads/waits for commands/response from the C&C
  • Send bot version
  • Send Bot ID
  • Send a "Pong" response to the C&C
  • Decode a Base64 encoded file to an executable file
  • Terminate itself
  • Update itself
  • Download and execute a file
  • Upload a file
  • Gather the following information from the affected system:
    • User name
    • Domain
    • Operating System Version
    • Privelege
    • System Language

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.764.03

FIRST VSAPI PATTERN DATE:

08 Feb 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

Identify and terminate files detected as BKDR_APTDOOR.A

[ 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 3

Search and delete this file

[ 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.
%User Temp%\chave.reg
%User Temp%\prap.bat 

Step 4

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.  %User Profile%\tmp

Step 5

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\CurrentVersion\Run
    • igfhelp = %User Profile%\tmp\hkcmd.exe

Step 6

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