Threat Description



Aliases: Funner.A
Category: Malware
Type: Worm
Platform: W32


Funner is a MSN worm that spreads by sending itself to the contacts listed in Microsoft's Windows Messenger.


Automatic action

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


Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

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

Technical Details

When executed, Funner will copy itself to the WINDOWS directory under the name rundll32.dll and alter registry entries to ensure the worm is started. It will also copy itself under WINDOWS SYSTEM directory as

explorer.exe   IEXPLORE.EXE   userinit32.exe  

The following registry keys are altered to ensure the worm runs upon next reboot

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run "MMSystem"     "c:\winnt\rundll32.exe "c:\winnt\system32\mmsystem.dll"", RunDll32"  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run "MMSystem"     "c:\winnt\rundll32.exe "c:\winnt\system32\mmsystem.dll"", RunDll32"  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon "Userinit"     "C:\WINNT\system32\userinit32.exe,"  

Funner also overwrites the local hosts file with a file containing various URLs.

NOTE! There is Windows system DLL named rundll32.dll under WINDOWS SYSTEM directory. This DLL is part of Microsoft Windows operating system.


F-Secure Anti-Virus detects Funner since the update published on October 11th, 2004:

Detection Type: PC
Database: 2004-10-11_01

Description Details: Katrin Tocheva, October 12th, 2004
Technical Details:Tzvetan Chaliavski, October 12th, 2004


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