Summary

Kelvir.f is a worm that uses MSN Messenger to send out a link. The link points to a site that contains self-extracting file which will install Kelvir.f and a new Sdbot variant.

Disinfection

To get rid of this worm it is enough to delete its files from the infected hard disk. The latest versions of F-Secure Anti-Virus can automatically disable (rename) the worm's infected files. If automatic disinfection fails, please select 'Delete' disinfection action for the worm's files when it is detected. Instructions are here:

http://support.f-secure.com/enu/home/virusproblem/howtoclean/howtodeleteinfec...

Please restart a computer after disinfection.

Additional Details

The self-extracting file is a PE executable, about 76K long. When run, it will create the Worm's folder:

C:\Program Files\RWNT3\

and place two files in there:

Fart.exe -- 19337 bytes long rwnt3.exe -- 6778 bytes long

It will also drop copy of the Sdbot into %SYSTEM% directory. Then the worm will alter registry entries to ensure that the Sdbot is activated upon reboot. There is no entry that activates Kelvir.h after the system is restarted.

HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ "Microsoft MSN Services" = "MSts32.exe" HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\ "Microsoft MSN Services" = "MSts32.exe" HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices\ "Microsoft MSN Services" = "MSts32.exe"

Detection

FSAV detects the dropper as component: Backdoor.Win32.SdBot.gen

Kelvir.f is detected with the following update:

[FSAV_Database_Version]
Version=2005-04-07_01

Technical Details: Tzvetan Chaliavski, April 6th, 2005;