Analysis by: Jed Valderama


Backdoor:Win32/Poison.E (Microsoft)


Windows 2000, Windows XP, Windows Server 2003


  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes


Infection Channel: Downloaded from the Internet

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


File Size: 32,936 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 26 Jun 2012
Payload: Connects to URLs/IPs

Arrival Details

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



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

  • dfgLYUT45

It injects threads into the following normal process(es):

  • explorer.exe

Autostart Technique

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

Active Setup\Installed Components\{C83EADBE-A0C7-19A8-501D-3A19D8877E63}
Stubpath = "%Current%\{malware filename}.exe"

Backdoor Routine

This backdoor connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED} - blocked
  • {BLOCKED} - blocked


It gets the default Internet browser of the affected system by querying the following registry entry:

(default) = "{path and file name of Internet Browser}"

It then injects a thread in the browser if an instance of it is running. If a running instance of the browser is not found, the malware opens a new process of the said browser where it injects its thread that connects to the remote server. This enables the remote user to execute arbitrary commands on the affected system.


Minimum Scan Engine: 9.200

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

Scan your computer with your Trend Micro product and note files detected as BKDR_POISON.HUQA

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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_LOCAL_MACHINE\Software\Microsoft\Active Setup\Installed Components\{C83EADBE-A0C7-19A8-501D-3A19D8877E63}
    • StubPath = "malware path and filename"

Step 5

Search and delete the file detected as BKDR_POISON.HUQA

*Note: Some component files may be 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.

To manually delete a malware/grayware file from the affected system:

  1. Right-click Start then click Search....
  2. In the Named input box, type the name of the file that was detected earlier.
  3. In the Look In drop-down list, select My Computer then press Enter.
  4. Once located, select the file then press SHIFT+DELETE to delete it.

Step 6

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