Wiping hard drive.

Discussion in 'Computer Support' started by carololine, Aug 15, 2006.

  1. carololine

    carololine Guest

    There was a programme on the TV today about how information is being stolen
    from dumped and donated P.C and laptops.

    What they are saying is that thieves are taking out the hard drive then
    getting personal information from the drive.

    They said it was impossible to remove all the information on a hard drive
    and the only way to ensure this was to smash the hard drive up with a

    What good is a donated P.C without the hard drive.
    I read in this group that killdisk will kill on the information on a hard
    drive is this correct.

    If killdisk will not do the trick are there other programs.
    If the TV presenter has got it wrong many people will be smashing up
    perfectly good hard drives thinking this is the only way to save your
    personal info.
    carololine, Aug 15, 2006
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  2. carololine

    Evan Platt Guest

    The best bet is to wipe your hard drive with a program that rewrites
    each sector of a hard drive one by one, and to do this 3 times.

    Could people with the right skills and the right tools still get your
    data back?


    Could the people with the right skills and the right tools get data
    off the hard drive smashed with a hammer? Yes.
    Have you priced hard drives lately?
    Evan Platt, Aug 15, 2006
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  3. carololine

    Plato Guest

    Just use a free zero fill utility.
    Plato, Aug 15, 2006
  4. carololine

    7 Guest

    Boot up under livecd like Mepis, Knoppix, DSL etc
    in a console window type
    dd if=/dev/zero of=/dev/hda
    (or its variants) to wipe your hard disk completely.
    7, Aug 15, 2006
  5. carololine

    beenthere Guest

    The presenter did mention Eraser, and Dban as two options.
    They`ll both Wipe a drive.
    beenthere, Aug 15, 2006
  6. carololine

    carololine Guest

    So you saw the programme.
    Yes he did mention Dban and Eraser but still said the best option was to
    smash the hard drive up with a hammer.
    carololine, Aug 15, 2006
  7. carololine

    anthonyberet Guest

    He was lying - the best option is to run Dban, then Eraser, and then
    smash the hard drive up with a hammer, and then melt it down.
    That could be overkill though - It depends how valuable the information
    on the drive is.
    anthonyberet, Aug 16, 2006
  8. carololine

    Daave Guest

    I've heard this, too.

    Can anyone explain this in layman's terms? Bits are zeros or ones. I
    would think that changing all the ones to zeros would be the answer.
    Obviously rewriting the entire data on the drive as zeros is not
    analogous (pardon the pun) to bulk-erasing a tape. But I wonder why. Is
    it somehow impossible to rewrite some of that data? And if so, why is it
    impossible? Or does some kind of memory still exist? But if this is so,
    how can memory exist in 100% zeros?
    Daave, Aug 16, 2006
  9. carololine

    Gubo Dangle Guest

    Daave formulated on Wednesday :
    Typical TV scare tactics. People 'format' the HDD thinking its enough
    to wipe the data.. and its not.

    If you wipe the drive with the correct tools, doing a multi-pass wipe
    with random data rather than just a zero fill, nobody is going to be
    able to get any useful info from it.

    There are special forensic tools that can (apparently) read some of the
    data hidden on the 'edges' of the magnetic tracks; but I'm skeptical
    such tools really exist for modern drives.
    Gubo Dangle, Aug 16, 2006
  10. carololine

    Daave Guest

    Random data sounds fine. Analogous (there's that word again) to the idea
    of white noise.

    What exactly is zero fill? Is that the same thing as making sure every
    blessed bit is a zero? Is this even possible?
    A ha. Data hidden on the edges? So it's possible there could be a
    smidgen of useful data left? I'd love to see a demonstration!
    Daave, Aug 16, 2006
  11. carololine

    Vanguard Guest

    Open the drive. Remove the platters. Sand the platters. Not only is
    the material used to encode the data now off the platters but it has
    been thoroughly randomized into dust. There is nothing that critical
    on your hard drive that would require such severe erasure. It is far
    easier to dupe someone into directly revealing their credit card
    number than to get it from a hard drive wiped with Eraser or KillDisk.
    After all, when have you EVER bothered to walk along with the waiter
    when you gave him the credit card number and made sure that someone
    the waiter never even saw the number on the card when he swiped it, or
    ran a trace on their dial-up service to make sure someone wasn't
    spliced in or provided them with a bogus reader that duplicates the
    data to the thief? Get a grip.
    Vanguard, Aug 16, 2006
  12. carololine

    thanatoid Guest

    Bullshit. Since when do you believe ANYTHING in TV news? Its
    primary purpose is to scare you so that you stay at home, and
    buy stuff off the shopping networks, period.
    thanatoid, Aug 16, 2006
  13. Actually, you should use a 'ammer, a bloody great big 'ammer.
    =?ISO-8859-1?Q?Brian_H=B9=A9?=, Aug 16, 2006
  14. Misinterpretation of a tv program and then usenet posts of what people
    think was said on a tv program is what is scary.
    The program showed that people think that deleting and formatting is
    enough, when in fact it leaves the data on the disc and just rearranges it.
    It also showed one firm of recyclers that removes the platters, breaks
    them up and *then* sends them off to be melted down.
    I think the latter is a sure fire method of putting someones mind at
    rest that their data has been destroyed.
    =?ISO-8859-1?Q?Brian_H=B9=A9?=, Aug 16, 2006
  15. carololine

    carololine Guest

    My only concern is that perfectly good hard drives are being smashed up on
    the advice of a TV expert when they P.C or laptop can be donated and used by
    others unable to afford one.
    carololine, Aug 16, 2006
  16. There is a big difference between donating your pc to someone who can't
    afford it, and taking it to a rubbish dump / recycling centre expecting
    it to be destroyed and finding out it has ended up in Nigeria stripped
    of your personal data.
    =?ISO-8859-1?Q?Brian_H=B9=A9?=, Aug 16, 2006
  17. carololine

    Gubo Dangle Guest

    Daave wrote on 16/08/2006 :
    Zero fill just writes Zero to every storage byte on the drive. Some
    drives - to attempt to improve performance - will recognise that its
    just about to write a sector of zeros and simply mark the sector as
    blank rather than actually erasing anything. Hence the need for a fill
    with random data to ensure everything has gone.
    Not quite hidden, but a combination of magnetic spread and the fact
    that (on older drives) the head coming from one direction can land in a
    slightly different place than when coming from the opposite direction.

    I'd be amazed if modern drives still have that 'feature' though as the
    data is now so tightly packed I doubt there would be room for such
    tolerance, and doing a random data wipe or two will overwrite 99.9% of
    any data that might of been recoverable anyway, so its not something
    worth worrying about.
    Gubo Dangle, Aug 16, 2006
  18. carololine

    Keme Guest

    The tracks have only gotten narrower. They still need some unused space
    in between, or there would be crosstalk and degradation. This "empty"
    space outside the formatted track can contain useful data.

    Magnetism is still "analog". That means that any "1" and "0" on the disk
    has a level influenced by the previous value. Depending on the
    resolution of the sensor reading the disk, even when reading on the
    track you can get 1-3 accurate generations of overwritten data. Forensic
    software can be used to "read between the lines", and deduce from that
    several generations of "erased" data with good accuracy.

    Well behaved software will always try to write on the track, so you need
    specialized software for a secure wipe between tracks. Doing 15-20
    passes of random writes on the tracks, and in 8-10 intermediate
    positions, should be safe. That means 120-200 complete disk writes,
    which would take a week or so on a reasonably sized disk.

    Maybe you could ask a hospital to take your disk through a magnet
    resonator for a couple of passes. Should be quicker, and the machine
    isn't limited by tracks. (Don't try to save money by keeping the HD in
    your pocket when undergoing examination, though...)

    This, of course, assuming that your castaway data is interesting to
    someone else. Disk forensics (data collection and analysis) takes time
    and effort, so very few do it for fun. Don't bother with extreme
    security unless you have something to hide. Zero fill is still safe
    enough for most of us.
    Keme, Aug 17, 2006
  19. carololine

    Gubo Dangle Guest

    Keme formulated the question :
    True - at least for now...
    Wouldn't that cause data errors??
    And probably a firmware change to allow the drive to actually write
    there in the first place, seeing as the firmware would be doing its
    hardest /not/ to write on the gaps.
    Gubo Dangle, Aug 17, 2006
  20. carololine

    Vanguard Guest

    So why you replying to my post? Did it look like I was the paranoid
    one. I noticed you managed to snip out all my content to make it look
    like you were replying to the OP.
    Vanguard, Aug 17, 2006
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