This virus infects the Master Boot Records of hard disks
and the DOS boot records of diskettes. It spreads only through
Urkel does not let the original partition table remain in its
proper place in the Master Boot Record, as most other MBR viruses
do. This causes the hard disk to be inaccesible after a floppy
boot, since the operating system cannot find valid partition data
in the Master Boot Record - attempts to use the hard disk result
in the DOS error message "Invalid drive specification".
When the computer is booted from the hard disk, the virus is
executed first, and the hard disk can thereafter be used
normally. The virus is not, therefore, easily noticeable, unless
the computer is booted from a diskette.
Do not use FDISK /MBR to clean Urkel: you will loose all your data.
Note: When disinfecting Urkel with F-PROT after a floppy boot,
use the command F-PROT /HARD /DISINF instead of using F-PROT C:,
or just run F-PROT in interactive mode and scan 'Hard disk' with
disinfection option on. After disinfection, error message 'No
hard disk found' is normal: just reboot after the disinfection is
done and you should see your hard drive again.
Urkel virus sometimes displays text 'Urkel' on screen.