Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

To mitigate damage from a virus infecting a Windows 7 MBR I boot into TrueCrypt encrypted windows from a CD (changed BIOS to boot CD first). I plan to boot other Operating Systems from external hard drives and feel removing the MBR is a wise step in prevent a virus from jumping from one of those to the main encrypted OS.

Googling shows the only way to remove an MBR is use Linux or remove the hard drive and connect to another machine. Is this true?

In summary I am looking for an easy way to achieve remove the MBR, preferably via a GUI as that will minimize risk of damaging any actual data. Perhaps it's possible to boot into Windows from an external hard drive then use DiskPart to clean the MBR on the internal drive (after selecting disk and partition).

share|improve this question

Boot into a linux live CD, and use this command:

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

(substitute /dev/sda for your HDD)

Be careful not to make a typo. If you forget the count parameter, it will erase your entire hard drive!

share|improve this answer
I verified that and see a lot of sites recommending it. The command ran as root from terminal on a USB Booted Ubuntu, but Windows could still boot from the hard drive so it cannot have worked. After searching and searching I decided to just zap the MBR partition and see what happens. It was a bad idea. The Trucrypt rescue disc could nothing but decrypt the drive. Decrypting took many hours and left the drive with one partition the size of the whole drive, but the data was there. Neither Windows 7 install CD or the TrueCrypt rescue disc could make it boot. I ended up re-installing Windows. – Paul Lockwood Aug 27 '12 at 19:18
@Paul I think truecrypt depends on some data in the bootloader, then. – kinokijuf Aug 27 '12 at 19:56
Perhaps it just needs to know where offset on the disk? When time permits I'll come back to this and post a solution here if there is one. This is just a 'nice to have' for me but surely others must really desire it for the extra protection – Paul Lockwood Aug 29 '12 at 12:00

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.