Kelvir.f, IM-Worm.Win32.Kelvir.f


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.


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:

Please restart a computer after disinfection.

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Technical 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.

 "Microsoft MSN Services" = "MSts32.exe"
 "Microsoft MSN Services" = "MSts32.exe"
 "Microsoft MSN Services" = "MSts32.exe" 

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

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