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View Full Version : truely Cleaning a hard disk



xds4lx
01-18-2003, 01:07 AM
Ive been thinking lately on ways to totally clean a hard disk to hide files or information. I know that you can download programs to do this that just dump meaningless information into the drive to cover up what was previously there. But does this really work good and provide an efficient method of covering up things? not that i have anything to hide but i bought a laptop from my dads company for $75 bucks, a pII 533 128mb pc133 22gb hd prettey decent, and they didnt even format the hd! I told my dad about that and they are looking into ways of taking care of this, i told him that formating doenst really work so is this a viable soloution?

dP munky
01-18-2003, 01:39 AM
try this thread http://www.cprogramming.com/cboard/showthread.php?s=&threadid=29879&highlight=dumb+question

foniks munkee
01-18-2003, 11:18 AM
Take the lid off - run it through a bulk eraser and fill the drive with epoxy resin. You would be surprised as to what they can get off a "formated disk".

I know that it is possible to retrieve data from a disk which has been formated (even low level formatted) a number of times.

no-one
01-18-2003, 03:26 PM
format 7 times. thats what the gov. says will clean it.

RoD
01-18-2003, 03:38 PM
Originally posted by no-one
format 7 times. thats what the gov. says will clean it.

ya lets listen to the goverment

</sarcasm>

no-one
01-18-2003, 03:58 PM
well then they did only format once the HDD's they sold to china from Los Alamos, that the chinese got an ass load of info from.

so its a pretty good assumption that more than that makes it hard for you to accidentally give information to the enemy. Oh wait they're allies now right(sarcasm).

::edited for posterity::

secondly, you'll all remember the Weekly World News report that hackers can make your computer physically explode and kill you remotely, so i'm sure nothings safe

ammar
01-18-2003, 04:35 PM
Originally posted by foniks munkee
Take the lid off - run it through a bulk eraser and fill the drive with epoxy resin. You would be surprised as to what they can get off a "formated disk".

I know that it is possible to retrieve data from a disk which has been formated (even low level formatted) a number of times.

Can you please explain more, I've never heard of this.

*ClownPimp*
01-18-2003, 06:53 PM
just delete all the files, then fill up the HD with zeros a few times. Once the data has been written over, its gone for good

foniks munkee
01-18-2003, 08:01 PM
Can you please explain more, I've never heard of this.

I am not sure of the techniques used exactly - but a (sort of) friend who works for the Australian federal police in a computer forensics lab described their ability to retrieve data from supposedly wiped disks. The way he described it was that a magnetic storage medium will contain residual traces of the data - even when overwritten, their job is to write programs and design hardware to retrieve this data and apparently it works.

I have also seen a rather amazing case where a guy in the US was convicted of murder and one of the key peices of evidence used was a floppy disk that contained a letter to a man who was hired to kill his wife. They were able to reconstruct the data from a floppy that was formatted then cut up into tiny peices with serrated scissors.

hostensteffa
01-19-2003, 01:25 AM
As a general rule, the data cannot be completely erased. No matter how many times you format, fdisk, etc, the data is still there until it is written over. Which is how the fbi, data recovery centers, and so forth can get data from formatted and damaged hard drives. There are some ways around this though, typically 3rd party software, i'm not sure about nowadays, but cleansweep used to do the job quite nicely, it would wipe the stuff clean off the drive, but then again who knows if it was legit, other than the fbi and such there's not much of a way to test this product, and if it did that they probably would not let it on the market, (typically speaking of the govt. in the states only, i'm not sure how that kind of stuff is overseas)

Davros
01-21-2003, 04:04 AM
Some of you may find this interesting:

http://news.bbc.co.uk/1/hi/technology/2676461.stm

Govtcheez
01-21-2003, 07:10 AM
>then fill up the HD with zeros a few times.

That won't do it - if you just copy 0s over it every time, everything's just at a lower voltage than before - it's still recoverable.

*ClownPimp*
01-21-2003, 07:27 AM
>That won't do it - if you just copy 0s over it every time, everything's just at a lower voltage than before - it's still recoverable.

Somehow i doubt that.... but okay, fill it up with random data!

Govtcheez
01-21-2003, 07:31 AM
OK, to simplify things, let's say a HD thinks a bit's at 1 if the voltage is between 5-10 and 0 if the voltage is 0-5. if you write zeroes over it, it won't take it all the way down to zero, just closer to it. Some of the data will still be recoverable... (there was a story on /. yesterday about this exact same thing (and the suggestion foniks munkee posted was exactly the same as one of the suggestions there) - check on it for more info)

Govtcheez
01-21-2003, 07:36 AM
This might help:
http://slashdot.org/article.pl?sid=03/01/20/1541233&mode=thread&tid=99

face_master
01-21-2003, 07:47 AM
I have also seen a rather amazing case where a guy in the US was convicted of murder and one of the key peices of evidence used was a floppy disk that contained a letter to a man who was hired to kill his wife. They were able to reconstruct the data from a floppy that was formatted then cut up into tiny peices with serrated scissors.I would have done the same thing, but burnt it (but then again, im not dumb enough to place incimidating evidence on a piece of digital media. A piece of paper burns pretty well ;)

As you can tell I like to burn things. My mum is still hassling me about the absence of grass in our backyard :)

I am Here
01-21-2003, 11:57 AM
I heard that filling the drive with random data 7 times, anything less than that can be considered recoverable.

RoD
01-21-2003, 03:23 PM
The only way to remove everything, is to destroy it, period.

Waldo2k2
01-21-2003, 08:14 PM
write 2's to the entire hdd 13 times and then the gremlins will come out and destroy the computer of anyone who tries to recover the data.:rolleyes:

itld
01-21-2003, 09:22 PM
howdy,
years ago i read that the US government used "A"'s and "8"'s they would first fill the entire disk with A's then fill the entire disk with 8's

M.R.

Leeman_s
01-21-2003, 11:13 PM
Just so you guys know......


When you format a hard disk, you are not really erasing the information at all. You are making the hard drive THINK that there is nothing there. Then it's able to be overwritten easily as the HD is saying there is no information on it.

Think of it like a flag that says "ooh we've got some stuff over here, over here, etc". You just make it say "ok we're all clean", but really isn't

dP munky
01-22-2003, 04:00 PM
when you say "write A's then 8's" how would you do that, you cant exactly go into memory and go, ok you are now a and you are now 8??? ... or am i wrong?

Waldo2k2
01-22-2003, 04:23 PM
Originally posted by dP munky
when you say "write A's then 8's" how would you do that, you cant exactly go into memory and go, ok you are now a and you are now 8??? ... or am i wrong?

Im assuming he means write the bitcode version of A and 8 (which is how it's saved on a hard drive in the first place)
8 in bitcode:
00010000

dP munky
01-22-2003, 04:31 PM
so youre saying open up notepad and in binary do one of these 1000
1000
1000
1000
1000
1000????



* i know this doesnt really matter, but i've heard this question a few times and seriously wonder how you would do that

Waldo2k2
01-22-2003, 04:37 PM
not quite
first of all, the text file adds organization to the drive, as well as an entry in the MFT...which is self destructive to the fact that you're trying to format the thing "for good".
You would write a program that's run from a floppy, it uses a for loop to sequentially write the bit code for 8 and A in your case to each sequential block until the end of the disk is reached.

dP munky
01-22-2003, 04:39 PM
gotcha! that makes a lot of sense. but i still insist the only way to truly get rid of the information is to burn that mutha....i just think that if it was that easy to do, the fbi wouldnt find stuff on pplz computers

Waldo2k2
01-22-2003, 04:47 PM
>>burn that mutha....

i completely agree
i had a hdd about a month ago, it got quick formatted (no biggy) then converted to ntfs, then fully formatted to fat32....still got data back

no-one
01-22-2003, 11:20 PM
>but i still insist the only way to truly get rid of the information is to burn that mutha

you only wish it was that easy... people pay to have the data recovered after the HDD has been burned and it can be done, even when the drive is burned so bad the casing has peeled open from the heat.

hey did you know they can see whats on your monitor from across the street?!!

The only, and i mean only way to keep them out of your private data is not to have it.

now go eat some cookies or something.

itld
01-22-2003, 11:36 PM
howdy,
THEY can see my CRT from accross the street, THEY can recover data from burnt HDD's, THEY can listen to what i say....

i don't know who THEY are but THEY are starting to ........ me off

::itld reaches for his tin foil hat and dark glasses, closes all o fhte window shades::

M.R.

dP munky
01-23-2003, 12:37 AM
"even when the drive is burned so bad the casing has peeled open from the heat."
If im gunna burn it, im gunna take the case off separate it and burn it and bury the ashes in different locations.

it doesnt really matter though if they wanna find out what you got they'll get it, but im gunna make it as hard as possible.

now YOU go eat some cookies or something.