Recovery using bad sectors / DBAN

[tosh.hdd]

Hey,

first of all I´d like to say that there is no really valuable data on my hdd in question. Nevertheless, i would appreciate your technical opinion (as I am not very competent in this context)

Recently, i erased my HDD using DBAN. Erasing worked fine, also the drive did not report any error before or showd any signs of malfunction in Usage before.
The drive contained some personal important data (financial/personal), thus i made the efford using dban before deposing the drive. Also, the HDD was quite new (2TB). Furthermore, I did some damage to the SATA/Power-Pins to prevent reuse/repair of the drive.

After this, i realized that even dban is no perfect method - assuming there were bad sectors on physical level, dban would not have erased them. While using google a bit, I came cross the statement that the HDD firmware erroneously can map even functional sectors as bad ones sometimes. Consequently, it is possible that personal data is still on the drive.

As said above, the controller is damaged. On the other Hand, Hardware gets repaired and refurbished. I dont think thats beeing done in this case. However, if it is easy to swap a ne controller-pcb to the drive - are the contents of unerased sectors now on the accessible HDD space?

As far as I understand, the Drive Firmware has a list containing all Bad sectors and their location (G-List). As long as the drive follows this list, the hdd ignores these sectors on hardware level and my data would be safe from other normal users. Would it also be safe if the controller-pcb is replaced? Or could the G-List information be lost and therefore the data be visible?

(I know that its even possible to access bad blocks contents ignoring firmware barriers in a lab - but as I have only normal personal data on my disk, no one would spend so much money on this i think. Nevertheless, I dont feel so comfortable realizing that dban isnt as secure as i thought.

regards,
Greg

[BGman]

Such a long post and not a word about the model of your HDD.

[tosh.hdd]

I am sorry. You are right, I forgot the model. Its a toshiba P300. However, i did not want to ask you for a detailled analysis of this particular Harddrive. Rather, I am interested in your general opinion. This will not have been the last Harddrive I give away, so I am interested in this aspect in general, independend of the specific model.

For example, the one question i mentioned wether it is common that there are "false" bad sectors due firmware bugs that are in fact full functional - or this is a very rare exemption. At least I did not hear this before.

[ShaneWard]

If you damaged the hard drive pins, then I guess you want to throw the drive in the bin without any chance of recovery. Best thing to do is if this is your path, Open the hard drive completely until you see the disk and heads, unscrew the disk from its spindle and then get a magnet and wipe it over the disk on both sides, then throw the whole thing in the bin. Nothing will be recoverable if you do that.

Another thing is, if you can't open the drive, is buy a really powerful magnet, and rub it both sides of the hard drive. It needs to be very strong magnet.

[tosh.hdd]

If you damaged the hard drive pins, then I guess you want to throw the drive in the bin without any chance of recovery. Best thing to do is if this is your path, Open the hard drive completely until you see the disk and heads, unscrew the disk from its spindle and then get a magnet and wipe it over the disk on both sides, then throw the whole thing in the bin. Nothing will be recoverable if you do that.

Another thing is, if you can't open the drive, is buy a really powerful magnet, and rub it both sides of the hard drive. It needs to be very strong magnet.

Yes, i know there are many possibilities. But as I said, for me they seemed a bit excessive in relation to the data importance. If there would have been really valuable business data on th drive I certainly would have contacted a professional company for data destruction. Until now, DBAN seemed to be a very reasonable way for this kind of task in private context.

I would just like to understand if the fact of "buggy bad sectors" - bad sectors that are not overwritten due erase because the HDD has them on GList, but are functional and readable in fact - is really true / if it is a real problem.

[ShaneWard]

I guess if the G-list is wiped, then the data on the sector could be accessible, or the computer will try and read and peace together the data before marking it bad again.

[tosh.hdd]

I guess if the G-list is wiped, then the data on the sector could be accessible, or the computer will try and read and peace together the data before marking it bad again.

yes, but wiping the g-list is an advanced technique i think, there are not many people who can (and want to) do this. My concerns about privacy refer primarily to people who bought the (refurbished/repaired) disk and are running an "deep scan" by recovery software for example. I did not ever anything to erase the Glist, I neither have the equipment nor an idea how to.

Even if the bad sectors could be read, this would not be a privacy problem as long as they are really bad (ecc checksums or so failed) - in this case only very advanced people could read remaining data fragments. But what about "false" bad sectors that are functional in fact and only were added to glist by firmware bug? As I said, one time i read this could happen sometimes.

I think that must be a very rare bug, because otherwise more concerns had been arised on this. In google i just found this one statement by a data recovery company, nothing more...

[DRUG]

Hey,

first of all I´d like to say that there is no really valuable data on my hdd in question. Nevertheless, i would appreciate your technical opinion (as I am not very competent in this context)

Recently, i erased my HDD using DBAN. Erasing worked fine, also the drive did not report any error before or showd any signs of malfunction in Usage before.
The drive contained some personal important data (financial/personal), thus i made the efford using dban before deposing the drive. Also, the HDD was quite new (2TB). Furthermore, I did some damage to the SATA/Power-Pins to prevent reuse/repair of the drive.

After this, i realized that even dban is no perfect method - assuming there were bad sectors on physical level, dban would not have erased them. While using google a bit, I came cross the statement that the HDD firmware erroneously can map even functional sectors as bad ones sometimes. Consequently, it is possible that personal data is still on the drive.

As said above, the controller is damaged. On the other Hand, Hardware gets repaired and refurbished. I dont think thats beeing done in this case. However, if it is easy to swap a ne controller-pcb to the drive - are the contents of unerased sectors now on the accessible HDD space?

As far as I understand, the Drive Firmware has a list containing all Bad sectors and their location (G-List). As long as the drive follows this list, the hdd ignores these sectors on hardware level and my data would be safe from other normal users. Would it also be safe if the controller-pcb is replaced? Or could the G-List information be lost and therefore the data be visible?

(I know that its even possible to access bad blocks contents ignoring firmware barriers in a lab - but as I have only normal personal data on my disk, no one would spend so much money on this i think. Nevertheless, I dont feel so comfortable realizing that dban isnt as secure as i thought.

regards,
Greg

My man, just open the drive and slam it with a hammer. No one will bother to recover after your first DBAN run.