It is a dangerous memory resident stealth boot virus. It hooks INT 13h and writes itself to the MBR sector of the hard drive and boot sectors of floppy disks that are accessed. The virus stores the original boot sector out of the "legal" disk area: on the track 80th. The INT 13h handler decrypts end displays the message once per hour, in case at this moment disk data are read or written:
CHUPACABRAS
