Funner is a MSN worm that spreads by sending itself to the contacts listed in Microsoft's Windows Messenger.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
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
Description Created: Katrin Tocheva, October 12th, 2004
Technical Details: Tzvetan Chaliavski, October 12th, 2004