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Memories of a Media Card

Posted by kdawson on from the embarassing-moments dept.

twistedmoney99 writes "Anyone who has upgraded their digital camera probably has a few older, incompatible media cards lying around — so why not post them on Ebay? Well, if you do, be sure to properly wipe them because the digital voyeurs are watching. Seth Fogie at InformIT.com purchased a bunch of used cards from Ebay and found recoverable data on most of them. Using the freely available PhotoRec application, he was able to extract pictures, movies, and more from apparently formatted cards. The picture is clear — wipe anything that can store digital data before getting rid of it."

9 of 266 comments (clear)

  1. I don't even bother to erase mine. by Anonymous Coward · · Score: 5, Funny

    It adds to the value on auction sites. A lot of people are willing to pay a fortune to see images of my dick.

    1. Re:I don't even bother to erase mine. by DaveM753 · · Score: 5, Funny

      You should try using a zoom lens.

      (Just kidding!)

    2. Re:I don't even bother to erase mine. by baldass_newbie · · Score: 5, Funny

      If it were small, he'd want a macro lens.

      You seem to speak from experience...

      --
      The opposite of progress is congress
  2. Memory effect by Anonymous Coward · · Score: 5, Informative

    Memory cards do not have nearly as strong of a memory effect as hard drives. With a hard drive you can write and rewrite multiple times and still have data recovered by someone willing to spend the time, effort, and money. But memory cards are much harder. You could be relatively sure of safety if you just:

    1. Delete everything on the card.
    2. Fill the card with something not private (maybe a text file that just repeats the same character).
    3. Delete everything on the card.
    4. If you're paranoid do 2 and 3 again.

    If you don't have a computer handy, you can accomplish step 2 by taking photos of a blank sheet of paper or a lenscap or something of that sort.

    1. Re:Memory effect by ivan_13013 · · Score: 5, Informative

      Whoa there. It is NOT bullshit. In fact it is COMPLETELY POSSIBLE to recover overwritten data from a hard drive, even if it was written over several times with random or nonrandom data. Remember that magnetic media cannot really store 1 and 0. It can only store a magnetic flux using ANALOG electronic components!

      The NSA today (and other people) can use Magentic Force Microscopy to extract enough detail to reconstruct what used to be on the drive. With only one or two overwrites, a sensitive oscilloscope could suffice.

      Here's one paper from ten years ago that talks more about the recovery technique.
      http://www.usenix.org/publications/library/proceed ings/sec96/full_papers/gutmann/

      From the paper:

      "In conventional terms, when a one is written to disk the media records a one, and when a zero is written the media records a zero. However the actual effect is closer to obtaining a 0.95 when a zero is overwritten with a one, and a 1.05 when a one is overwritten with a one. Normal disk circuitry is set up so that both these values are read as ones, but using specialised circuitry it is possible to work out what previous "layers" contained. The recovery of at least one or two layers of overwritten data isn't too hard to perform by reading the signal from the analog head electronics with a high-quality digital sampling oscilloscope, downloading the sampled waveform to a PC, and analysing it in software to recover the previously recorded signal. What the software does is generate an "ideal" read signal and subtract it from what was actually read, leaving as the difference the remnant of the previous signal."

  3. Re:speaking of wiping data by timeOday · · Score: 5, Insightful
    dd bs=1024 if=/dev/random of=/dev/sda1
    That was my system boot partition, you insensitive clod!

    As for erasing solid state media, I'd feel perfectly safe simply overwriting it with zeroes, one time over.

    I realize years ago magnetic media were written sparsely (inefficiently) with sloppy positioning mechanisms, but those days are long gone. I'd be really impressed to see somebody recover overwritten data on a hard drive instead of just talking about it.

    As for flash memory, I'll believe it when I see it.

    As for leaking information through discarded camera memory cards in the first, place, it's about the 1000th thing down my list of privacy concerns, way down below "binoculars." If you want to see pictures of random people's snapshots of each other, they're all over the web. How many of us really use our digicams to capture super-secret info? I just can't bring myself to care when I know databases of thousands of credit card numbers and SSNs are being bought and sold on the black market.

  4. Re:speaking of wiping data by croddy · · Score: 5, Informative

    Better (and more convenient) than dd'ing from /dev/urandom is wipe(1). It will, at your option, overwrite the disk using 34 different byte patterns, 8 of which are random.

    Its man page is also the only one I know of that uses the phrases "rising totalitarianism", "Department of Homeland Security", and "THIS IS AN EXTREMELY DANGEROUS THING TO DO".

  5. Re:speaking of wiping data by phalse+phace · · Score: 5, Funny

    "What are the best methods for removing almost any record of data?"

    Have Chuck Norris give it a roundhouse kick.

  6. Re:dd /dev/random by Anonymous Coward · · Score: 5, Funny

    Bols, I don't get it: are you actually saying there's NOT ENOUGH randomness out there?

    Here, have some of mine: ldjaofp9 bpm ]ak e]-07