From: peterharvey at emergency.qld.gov.au (Peter B. Harvey (Information Security))
Subject: Erasing a hard disk easily

Hi all,

As it was pointed out to myself there is still technologies which can bypass this. If you are workign with high sensitivity data then physical distruction is always the best course of action. Below is considered a basic sanitation to the media. Virtually impossible refers to the fact that most people don't have access to tunneling electron microscopy equipment to read the data.

If however you do require further sanitation you can obtain a Degauser (see DSD Authorised Products list for the Government recommended products for this purpose).

Regards
Peter

-----Original Message-----
From: Peter B. Harvey (Information Security)
Sent: Tuesday, July 13, 2004 9:59 AM
To: Gregh
Cc: full-disclosure@...ts.netsys.com
Subject: RE: [Full-Disclosure] Erasing a hard disk easily



Standard data recovery tools will be stopped by writing zeros to the disk. This includes programs such as OnTrack Data Recovery Pro.

However i have been informed that equipment exists to retrieve data that programs on a normal system cannot. Hence the writing multiple times with all 0 then all 1 then all 0 will cycle the disk so that it is virtually impossible to determine the residual data (please note all 1 means all bits are 1).

My two bits

Peter

-----Original Message-----
From: Gregh [mailto:chows@...mail.com.au]
Sent: Tuesday, July 13, 2004 8:20 AM
To: full-disclosure@...ts.netsys.com
Subject: Re: [Full-Disclosure] Erasing a hard disk easily



----- Original Message -----
From: "Maarten" <fulldisc@...ratux.org>
To: <full-disclosure@...ts.netsys.com>
Sent: Tuesday, July 13, 2004 7:23 AM
Subject: Re: [Full-Disclosure] Erasing a hard disk easily


>
> An overwrite with all zeros will -allegedly- not withstand a serious
> data-recovery attempt by professionals, not even when repeated.

I know you stated "allegedly" but this subject interests me. Many years ago,
a good friend of mine who had been in to pirating and suddenly realised he
could end up behind bars if he was ever caught got the shakes thinking about
it. He deleted it all and I let him know that wasn't good enough. He got
hold of a simple basic program that kept looping until the disk was full,
writing a line of 80 of the number "8" to the disk making one file that got
bigger and bigger until, ultimately, it filled the disk. Once filled, it
would close the file and all you had to do was boot into DOS and delete it
and the space was free once more all overwritten with the number "8"
wherever you looked with a sector editor.

Since that time I have seen sensationalist TV shows showing how FBI and CIA
operatives get stuff out written to a sector BEFORE the sector was
overwritten and I honestly cannot understand how that could be, if at all
possible. Am I right in thinking those shows are bull?

Greg.

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_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.netsys.com/full-disclosure-charter.html

This correspondence is for the named persons only.
It may contain confidential or privileged information or both.
No confidentiality or privilege is waived or lost by any mis transmission.
If you receive this correspondence in error please delete it from your system immediately and notify the sender.
You must not disclose, copy or relay on any part of this correspondence, if you are not the intended recipient.
Any opinions expressed in this message are those of the individual sender except where the sender expressly,
and with the authority, states them to be the opinions of the Department of Emergency Services, Queensland.

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