Master boot record

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Editing/replacing MBR contents

The Master Boot Record (MBR) is a 512 byte space created alongside the primary partition of a drive. The MBR may be used for one or more of the following:

  • Holding a disk's primary partition table.
  • Bootstrapping operating systems, after the computer's BIOS passes execution to machine code instructions contained within the MBR.
  • Uniquely identifying individual disk media, with a 32-bit disk signature; even though it may never be used by the machine the disk is running on.

Malware-infected records cannot be removed during a simple format; it must be overwritten completely with the following example linux command:


 dd if=/dev/zero of=/dev/sdb bs=446 count=1

Boot Record Fix

Please note that the following fixes are for instances of a single operating system installation. Do not attempt the instructions below with a computer running more than one operating system.

Vista/Windows 7

Boot into the Windows Vista or 7 disc. When available, click on the command prompt and enter, bootrec /FixMbr at the prompt and follow the instructions.

See Other

External Links