Analysis by: Kathleen Notario


Windows 2000, XP, Server 2003


  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes


This backdoor may be downloaded from remote sites by other malware.

It opens a hidden Internet Explorer window.

It deletes itself after execution.


File Size: 27,136 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 14 Sep 2010
Payload: Compromises system security

Arrival Details

This backdoor may be downloaded from remote site(s) by the following malware:



This backdoor drops the following copies of itself into the affected system:

  • %Windows%\EXPL0RER.exe

(Note: %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:

Active Setup\Installed Components\{CBFCF6A3-403D-98F9-223F-03EB127AFEE0}
StubPath = %Windows%\EXPL0RER.exe

Other System Modifications

This backdoor adds the following registry keys:

Active Setup\Installed Components\{CBFCF6A3-403D-98F9-223F-03EB127AFEE0}
{Defaul} =

Backdoor Routine

This backdoor opens a hidden Internet Explorer window.

Other Details

Based on analysis of the codes, it has the following capabilities:

  • This hidden web browser process contains the backdoor component, which connects to the following remote server and wait for commands: {BLOCKED}
  • The server sends encrypted codes to the client. The client then decrypts and executes these codes in the system.
  • Some of the actions that this server can perform are the following: get system information get username and hostname of the client

It deletes itself after execution.


Minimum Scan Engine: 8.900

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 malware files dropped/downloaded by BKDR_POISON.AKD


Step 3

Restart in Safe Mode

[ Learn More ]

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\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {CBFCF6A3-403D-98F9-223F-03EB127AFEE0}

Step 5

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