Short for Master Boot Record,
a small program
that is executed when a computer boots up
. Typically, the MBR resides on the first sector
of the hard disk
. The program begins the boot process by looking up the partition table to determine which partition
to use for booting. It then transfers program control to the boot sector
of that partition, which continues the boot process. In DOS
systems, you can create the MBR with the FDISK /MBR command.
An MBR virus is a common type of virus that replaces the MBR with its own code. Since the MBR executes every time a computer is started, this type of virus is extremely dangerous. MBR viruses normally enter a system through a floppy disk that is installed in the floppy drive when the computer is started up. Even if the floppy disk is not bootable, it can infect the MBR.