Threat description




Bropia.F is a minor variant of Bropia.A. Like the previous variants, it uses MSN messenger for spreading. It also drops a variant of Rbot on the infected system.


Automatic action

Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.

More scanning & removal options

More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.

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

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Technical Details

When run, the worm copies itself as "msnus.exe" in the Windows system directory. Then it checks files:

winhost.exe  winis.exe  dnsserv.exe  

If these files are not found, it drops file "cz.exe" and executes it. This file is a variant of Rbot. When "cz.exe" is run, it copies itself as "winhost.exe" in the Windows system directory and adds the following registry keys:

[HKLM\Software\Microsoft\Windows\CurrentVersion\Run]  "win32" = "%SysDir%\winhost.exe"  

This ensures that it will be executed at next system startup. The bot can be used as a backdoor, collecting system information, logging keystrokes, relaying spam and for various other purposes.Brobia.F also drops a file "sexy.jpg" and opens it. On default installation of Windows, the program associated with jpg-extension is usually Internet Explorer. When opened with Internet Explorer, the picture looks like this:

MSN spreading

The worm copies itself in C-directory using one of the following filenames:

LOL.scr  Webcam.pif  bedroom-thongs.pif  naked_drunk.pif  LMAO.pif  ROFL.pif  underware.pif  Hot.pif  new_webcam.pif  

Then it attempts to send this file using MSN messenger to all active MSN contacts. The recipient has to accept and open the file to get infected by the worm.


F-Secure Anti-Virus detects Brobia.F with the following update:

Detection Type: PC

Database: 2005-02-03_01

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