BootSect.exe and BootRec.exe are both components of Windows Vista and later. They help make disks bootable.
Both are included with a Windows DVD or ISO but are not installed.
/mbr switches. It can be found in the “boot” folder, at the root of the Windows DVD.
/RebuildBCD switches. However, it is harder to find. It is only exposed if a computer is booted into Windows Setup or Windows Recovery Environment. Otherwise, one has to extract it from the “boot.wim” file in the “sources” folder of Windows setup disc, or the “winre.wim” file in a subfolder of “C:\Recovery” folder (although you might not find such a file), via DISM or 7-Zip. Once either of the two images of “boot.wim” are mounted or opened, BootRec.exe can be located under “Windows\System32” subfolder.