Wipe PC hard drives with a bootable 'Danger' floppy

by Bill Detwiler | Oct 13, 2003 7:00:00 AM

Tags: Bill Detwiler, Ted Laun, floppy disk, Efdisk, hard drive, Autoexec.bat, PC

Takeaway: When you need to wipe dozens of hard drives, a correctly configured, bootable floppy can save you time and effort. Find out how to create a 'Danger' disk that uses the Efdisk and Wipe utilities to do the job automatically.

Before you trash, donate, sell, or reuse an old PC, you should always wipe its hard drive. This is often a quick process when performed on a single machine, but performing this same task on dozens of machines can take much longer. If you need to wipe the hard drives on multiple machines, a bootable floppy using the Efdisk and Wipe commands can cut the job down to size.

Necessity is definitely the mother of invention
When Ted Laun, IS technician for CNET Networks, had 80 old PCs that were being taken out of service, he needed a quick, easy, and cheap way to wipe the contents of their hard drives. Unfortunately, the following conditions limited the wiping methods he could use:

The PCs were being sold so he couldn't physically destroy the drives.
He didn't have time to physically remove the drives and use a bulk eraser or strong magnet to scramble their contents.
The PCs had already been removed from their locations and no longer had keyboards, monitors, or mice connected.

With these restrictions in mind, Ted decided to create a bootable floppy that would automatically delete all of a hard drive's partitions, wipe all the drive's data, delete the master boot record (MBR), and alert him when the job was finished. Because his creation would be so destructive, Ted dubbed it the "Danger" floppy and decorated it with a skull and crossbones to prevent himself or anyone else from accidentally using it.

Creating a Danger floppy
To create his Danger floppy, Ted began with a clean boot disk created using Windows 98. This boot disk contained the Command.com, Io.sys, and Msdos.sys files. He then added the Efdisk.exe command line partitioning utility, IBM's Wipe.com hard drive wiping utility, and the freeware Beep.exe program that would generate an alert when the wiping process is complete. Finally, Ted created an Autoexec.bat file that would use the aforementioned programs to wipe the hard drive. The following is the text of that Autoexec.bat file:
Efdisk /delall

echo Y | wipe 0

Efdisk /mbr

:mary
@echo off
BEEP /HE /L500
BEEP /HD /L100
BEEP /HC /L300
BEEP /HD /L300
BEEP /HE /L300
BEEP /HE /L300
BEEP /HE /L700
goto :mary

The Autoexec.bat file's first line of code uses the Efdisk utility with the /delall switch to remove all partitions on the hard drive. The second line uses the wipe utility to write zeros to the hard drive (which overwrites the drive's contents). Ted also uses the echo Y setting with the Wipe command to automatically answer "Yes" to prompts for confirmation. The third line of code uses the Efdisk utility to rewrite the drive's master boot record. The drive should then void any sensitive data that existed before the wiping process started.

To finish up the Autoexec.bat file, Ted wanted his Danger floppy to alert him when the process was complete. Since the machine wouldn't be connected to a monitor, a visual message wasn't possible. Instead, Ted used the Beep utility to generate a series of tones on the PC's internal speaker. The code for these tones is located within the Autoexec.bat's Mary subroutine and, when played, generates a rather nice rendition of "Mary Had A Little Lamb." The final line of code causes the tones to repeat indefinitely, to make sure Ted knows the process is complete.

Using the Danger floppy and potential problems
Using the Danger floppy couldn't have been easier. Ted connected a dozen or so PCs to power cables, inserted a copy of his Danger floppy, and powered on one of the systems. When the PC began to play "Mary Had A Little Lamb," he knew the hard drive had been wiped. He could then power off the machine and remove the Danger floppy.

There were a handful of machines on which the Danger floppy did not work. These machines either had broken floppy drives, didn't have the floppy drive in the boot order, or the BIOS required a keyboard to boot. When Ted encountered a machine that wouldn't run the Danger floppy, he connected a keyboard and monitor to diagnose and resolve the problem. Even with these interruptions, Ted was able to wipe the hard drives on over 80 machines in just a few hours.

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