Antivirus software company Symantec is warning of a new macro virus targeting Microsoft Word.

The virus can overwrite the Master Boot Record (MBR) of any physical hard drives on a computer.

Dubbed W97M.Killboot, the virus infects a currently active document and the Normal.dot template when an infected document is closed. Any documents will be infected when they are closed.

But it also creates the file C:\Setver.exe, which the Symantec antivirus products detect as Trojan.Killboot.

If Trojan.Killboot is run, it writes the viral code into the MBR which can then overwrite the MBR on all physical hard drives with zeroes.

So far there have been few reports of the virus in the wild.