How to Completely Erase a Hard Disk Drive


How to Completely Erase a Hard Disk Drive
Issue 08
Volume 8
August 2010
How to Completely Erase a
Hard Disk Drive
So…you've decided to donate your old computer to a charity, local
group or school. Good for you! Now here are some tips to avoid
data theft when donating a computer system. It's important to make
sure your computer's hard drive is completely free of data.
In the "no good deed ever goes unpunished" department, you need
to ensure that you don't donate more than you planned. The last
thing you want is to pass on a PC with sensitive business information,
or even personal information such as stored passwords, personal
documents and credit card numbers that could be retrieved.
There are many ways to go about ensuring your data can never be
retrieved. Obviously, you can choose to physically smash the drive,
but there are alternatives that enable you to keep the system intact
so you can donate a complete system.
Erasing and Formatting: Just Not Secure Enough
Simply erasing all the data on your hard drive and formatting it is not
enough security. You can spend hours going through your hard drive
and deleting all the files and documents you want, but using the
delete key on your keyboard in Windows basically only removes the
shortcuts to the files making them invisible to users. Deleted files still
reside on the hard drive and a quick Google search will show many
options for system recovery software which will allow anyone to
reinstate that data.
Formatting the hard drive is a bit more secure than simply erasing the
files. Formatting a disk does not erase the data on the disk, only the
address tables. It makes it much more difficult to recover the files.
However a computer specialist would be able to recover most or all
the data that was on the disk before the reformat.
For some businesses and individual users, a disk format may be
secure enough, depending, of course, on the type of data and
information saved to the computer. It is not 100 percent safe, but if
you have decided a disk format is a good choice, at the very least to
do a full format rather than a quick format.
Disk Wiping Options (aka Data Dump)
Even more secure than reformatting is a process called disk
wiping. The term disk wiping is not only used in reference to
hard drives but any storage device such as CDs, RAIDs, thumb
drives and others. Disk wiping is a secure method of ensuring
that data, including company and individually licensed software
on your computer and storage devices is irrecoverably deleted
before recycling or donating the equipment. Because
previously stored data can be brought back with the right
software and applications, the disk wiping process will actually
overwrite your entire hard drive with data, several times. Once
you format, you'll find it all but impossible to retrieve the data
which was on the drive before the overwrite.
While disk wiping algorithms
differ from product to product,
they all will generally write the
entire disk with a number (zero
or one) then a reformat will be
needed. The more times the
disk is overwritten and formatted
the more secure the disk wipe is,
but the trade-off is the extra time
to perform additional rewrites. Disk wipe applications will
typically overwrite the master boot record, partition table, and
every sector of the hard drive.
There are a variety of products available for different operating
systems that you can purchase or freely download online to
perform more secure disk wipes. If time to perform the disk
wipe is a consideration, there are also tech security companies
who offer disk wipe services.
Source:, August 28, 2009
Did You Know...
In 2003 two MIT students purchased 158 used disk
drives from various locations and found more than
5,000 credit card numbers, medical reports, detailed
personal and corporate financial information, and
several gigabytes worth of personal e-mail and
pornography on those drives.
Wiping or erasing applications
Stories of Data Passed…
To be sure that your data is removed beyond all practical ability to
recover it, you should use a wiping or erasing utility. These tools
overwrite every sector of the hard drive with binary 1's and 0's. Those
that meet government security standards even overwrite each sector
multiple times for added protection.
April 1997
A woman in Pahrump, NV, purchases a used IBM PC
and discovers records from 2000 patients who had
prescriptions filled at Smitty’s Supermarkets pharmacy
in Tempe, AZ.
CyberScrub cyberCide 3.0
"Delete" or "Format" doesn't mean Erase
Whether your data is sent to the recycle bin or your entire drive is
formatted and repartitioned, the chance of unauthorized discovery is
very real and poses issues of risk and liability. Securely wipe hard
drives and overwrite, delete and destroy privileged data with
cyberCide employs advanced hard drive erasure options that will
defeat software OR hardware forensic recovery. cyberCide provides a
cost effective solution for the critical task of data destruction and
wiping files.
White Canyon WipeDrive
WipeDrive has been used to erase hard drive data on over 20 million
hard drives! It is approved by the Department of Defense, and it is
trusted by government agencies and major corporations. Think of a
video tape that is full of recorded TV shows on it. The only way to get
rid of the old shows is to tape over it.
Using WipeDrive is like finding a channel completely full of static and
then recording over the entire tape. Using WipeDrive before getting rid
of your computer will completely erase hard drive data and protect
yourself from identity theft.
Kroll Ontrack Eraser Software
Ontrack Eraser software is an easy-to-use, highly flexible data erasure
tool that erases all traces of data stored on a targeted media ensuring that sensitive information does not fall into the wrong hands.
The overwriting procedures used by Ontrack Eraser to permanently
remove data meet the most stringent standards for data removal;
including those of the U.S. Department of Defense and the National
Industrial Security Program and CESG standards in the U.K.
Are there topics that you would like to have covered in future newsletters? We are
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August 2001
More than 100 computers from Viant with confidential
client data sold at auction by Dovebid.
Spring 2002
Pennsylvania state Department of Labor and Industry
sells computers with “thousands of files of information
about state employees.”
August 2002
Purdue student purchased used Macintosh computer at
equipment exchange; computer contains FileMaker
database with names and demographic information of
100 applicants to Entomology Department.
In an independent study, 10 used computers were purchased
from a computer store. Below are the findings:
Computer #1 - File server from a law firm which still had client
documents on it.
Computers #2-#5 – One was a server from a law firm, one had
a database of mental health patients, one still had Quicken files
on it, and one had a draft manuscript of a novelist.
Source: Remembrance of Data Passed: Used Disk Drives and Computer Forensics,
Simson L. Garfinkel
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