Cinderella was found in Finland in June, 1991.
It infects all COM-programs which are longer than 390 bytes.
Due a programming error, Cinderella may infect files with extension CO, DOC, OC or no extension at all.
Cinderella counts the user's keypresses and activates after a certain amount. Then the virus creates a hidden file named cInDeReL.la and resets the computer.
Virus stores itself to low system memory, on the interrupt table. Therefore it does not reduce available DOS memory while resident.
There are several variants.