F-Secure Virus Descriptions : Bropia.F

[Summary] | [Detailed Description] | [Detection]

NAME:	Bropia.F
ALIAS:	W32/Bropia.F, IM-Worm.Win32.Exir.a

Summary

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.

Detailed Description

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.

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Detection

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

[FSAV_Database_Version]

Version=2005-02-03_01

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Technical Details: Jarkko Turkulainen, Feb 03rd, 2005;

F-Secure Corporation