Threat Description



Category: Malware
Type: Trojan
Platform: W32
Aliases: Mitglieder.AI, I-Worm.Bagle.v, TrojanProxy.Win32.Mitglieder.AI, W32/Mitglieder.AI, W32/Bagle.x!proxy


A new Mitglieder proxy trojan appeared on April 7th 2004. It installs itself to system and works as a mail relay on port 14247. The trojan connects to several websites to report its port and ID. Similar Mitglieder trojan variants were dropped by certain Bagle worms in the past.


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More scanning & removal options

More information on scanning or removal options is available in the documentation for your F-Secure security product on the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for more information.

Contact Support

For further assistance, F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.

Technical Details

The Mitglieder.AI's file is a PE executable 7824 bytes in size packed with FSG file compressor.

According to our partner, the trojan was spammed in e-mail messages that had the following text:

We agree with your terms. The deal is acceptable.  For more information please read attached document.   Thank you.  Lisa Marlow.   

When the trojan's file is run, it copies itself as WINDOW.EXE file to Windows System folder and creates a startup key for this file in the Registry:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Run]  "window.exe" = "%winsysdir%\window.exe"   

where %winsysdir% represents Windows System folder name.

Then the trojan opens a backdoor on port 14247, listens for remote commands and works as a mail relay. The trojan connects to several websites to report infected computer's IP address, ID and proxy port.

This Mitglieder variant doesn't kill processes of security and anti-virus software.


F-Secure Anti-Virus detects Mitglieder.AI trojan in the following update:

Detection Type: PC
Database: 2004-04-07_02

Technical Details:Alexey Podrezov, April 7th, 2004


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