Recovering Data from a 1-Pass Zero'd Hard Disk Drive

Question

I don't want to do this, but I'm wondering how easy it is to do? Or to put it another way, I'm wondering "is a 1-pass zero of a drive enough?"

From what I understand, it's completely wiped from anyone that would try to recover data by connecting the drive to a device, NOT opening it. Is this accurate?

What about "government level" data recovery? What I've read suggests that under some circumstances, if you have the right kind of scanner, you can infer the previous state of a bit based on how "1" and how "0" it currently is. While that does make sense, it seems very unlikely that you could string enough of them together to get a useful block of data. And these blocks are scattered all over the drive. And you don't know if you are scanning "real" data, or old data that was previously erased long before the zero. Is there really a way you can get anything more than random data from a zero'd drive?

Also, what if it's not a zero pass, what if it's a 1-pass random data write?

To me, it does not seem realistic to every be able to get any useful data from a drive like this. That said, I usually do a 3 pass zero anyway :)

To clarify, I'm referring only to traditional spinning magnetic media hard disk drives. I'm not talking about SSDs, magnetic tape, or any other exotic storage devices. Just hard drives.

Answer 1

There are many tales suggesting otherwise, but all of those refer to decades old obsolete technology. The net result is that a single pass write of zero, or anything else, is sufficeient to preclude useful recovery.

Stories or theories involving magnetic force microscopes, etc., simply don't work for Terrabyte level drives. Millions of dollars of laboratory effort might recover a handful of bytes, but as a level of reference, no forensic group is going to do anything with it.

Now there is a separate question as to whether everything was zero'd (protected areas, or bad sectors), but anything written once is effectively gone.