Polyboot.B does not infect files and it has not any destructive effects in the computer. Polyboot.B has the following effects:

• It infects the boot sector of floppy disks (Boot) and hard disks (Master Boot Record).
• It infects all floppy disks used on the affected computer, provided that they are not write-protected.
• It prevents the computer from starting up correctly.

Polyboot.B infects the boot sector of hard disks and floppy disks. It has the following routine:

• It copies the original boot sector in the final sectors of the first track.
• It copies the virus code to the first sectors of the disk.
• By doing this, it goes memory resident. From then on, it can infect all floppy disks used on the computer.

Polyboot.B only spreads through floppy disks, in the following way:

• It infects the hard disk of the computer, when it is booted from a floppy disk infected by the virus. 
• It infects all floppy disks used in the affected computer. These floppy disks will then infect other computers.

Other interesting characteristics of Polyboot.B are:

• Part of its virus code is encrypted through a simple function with a one byte mask.
• It uses stealth techniques in order to avoid being discovered. When it goes memory resident, it reduces the amount of conventional memory that can be seen from MS-DOS by two kilobytes. At the same time, it copies its virus code in the top of the conventional memory and it goes memory resident.
• The code of Polyboot.B contains the following text: 31/03/98 WYX.