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Un-deletion software

Xpl1c1t

Limp Gawd
Joined
Jan 29, 2004
Messages
478
Sorry to post about software in a hardware forum but this question regards the integrity of hard drives. I recently told my father that i would be selling his old laptop soon, he advised me to perform what he called a "military wipe" of the harddrive to guarantee that no recoverable files would be left. I have never heard of something like this but is there software that can recover deleted data? I told him i had reformatted the system but he still insisted that I do this, I find it hard to believe that there is software that can recover deleted/formatted data. Dont hard drives fill deleted sectors with blank binary 0101...???
Well, tell me what you know, i'll be pretty scarred if this turns out to be true.
 
All a format does is rebuild the filesystem information, it doesnt do squat to the actual drive. :)

You can recover data from a format with a somewhat specialized linux boot disk. Its scary easy. (The coroner's toolkit, tct)

What your friend is suggesting is some sort of utility that writes random data/zero'es/ one's/ multiple times to some sort of "Department of Defence" specification. Its not totally foolproof, but the average joe with free software cant do much with it.

If you just delete and format, someone could take that drive and recover some data.

If you are selling it to mom or dad, forget the uber-wipe and let them have the drive. If yer selling it to someone who "buys used HDDs" Yeah, I'd wipe it multiple times.
 
Some HDD manufacturers have a zero-fill utility available for download. If that doesn't work, I think the Ultimate Boot CD contains one or two generic ZF utils ( www.ultimatebootcd.com )

Ideally what you'd want to do is write all zeros, all ones, and then several random patterns to the drive to wipe it. Whether any freeware utilities exist to do this, I don't know. A former coworker wrote an app to do it, but it was company property and I couldn't legally keep it when I left the company :(

edit: and yes, it's very easy to recover deleted/formatted data. Generally when you delete something the data isn't overwritten; basically all the system does is remove the references to the data from the file allocation table. So there's no longer anything pointing to the data, but it's all still there. When you format, you're not overwriting everything either. The FAT is completely cleared and the drive is checked, but most formats will leave the majority of your data alone.

To test this at one company I was at, we loaded several drives full of large images (both pictures and CD images). On one we deleted them, another we formatted, et cetera. We were able to recover nearly 100% of the data on anything short of a complete format and reinstall of the operating system--reinstalling it wrote over some of the old data. It took a zero fill, a one fill, and a random write to reduce the data to being completely unreadable.
 
Thanks for the very informative responces, it seems that what I was afraid of is reality, damn.
I should get this software immediately.

Thanks again
 
Xpl1c1t said:
Thanks for the very informative responces, it seems that what I was afraid of is reality, damn.
I should get this software immediately.

Thanks again

Download the UBCD I linked above. It's got four hard drive erase utilities that might suit your needs. I'm using it to wipe hard drives for my company before we sell the systems.
 
For business and personal reasons I have software that will recover ANYTHING from a harddrive. Shredding the data is the only possible way for me to not recover it and even then I'm not sure. I haven't tried after a shredding.
 
Xpl1c1t said:
Thanks for the very informative responces, it seems that what I was afraid of is reality, damn.
I should get this software immediately.

Thanks again
Try a Knoppix or similar Linux boot cd. You can do something like "dd if=/dev/urandom of=/dev/hda" and it'll overwrite with random bits. Substitute "zero" for "urandom" and it'll write zero bits. That is, bits that are zeroes, not zero bits. ;)
 
SirKenin said:
For business and personal reasons I have software that will recover ANYTHING from a harddrive. Shredding the data is the only possible way for me to not recover it and even then I'm not sure. I haven't tried after a shredding.

I use Ontrack's software for data recovery as part of my consulting practice and tested various methods of "wiping" a disk clean. I can attest a DoD wipe makes *any* software based recovery impossible.

But to be on the safe side I perform disk wipes with 12 passes of alternating 0s and 1s, then the last pass random data is written to the drive. :p
 
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