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Does zero filling a HDD really delete all data on it?

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December 19, 2007 4:42:10 PM

I know of HDD utilities that can recover data that has been deleted from the recycle bin. Does zero filling a hard disk drive really make all data on it totally unrecoverable?

December 19, 2007 4:54:33 PM

No.
The more times you do this the harder it is to retrieve the data.

If you do this a couple of times, you should be relatively safe.
However, the Gov't if it really wants to can do amazing things to get at the data.

Most ordinary hackers will not get past the 0 wiping.
December 19, 2007 5:01:18 PM

Run the zero filling about 10 times. If you are really paranoid, BURN the drive and buy a new one.
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December 19, 2007 5:05:16 PM

kittyhawk said:
I know of HDD utilities that can recover data that has been deleted from the recycle bin. Does zero filling a hard disk drive really make all data on it totally unrecoverable?



If you really need to make the data unrecoverable then get a program called Darik's Boot and Nuke. It's free. Just be careful with it... I never boot up DBAN on a PC unless I want the data on EVERY DRIVE permanently deleted.
December 19, 2007 5:12:11 PM

The data may still be accessible with very high end tools (think of Mission Impossible 3), but will a single zero fill make the data inaccessable via most data recovery software in the market today?
December 19, 2007 5:15:50 PM

What are you trying to hide anyway?
December 19, 2007 5:48:31 PM

kittyhawk said:
The data may still be accessible with very high end tools (think of Mission Impossible 3), but will a single zero fill make the data inaccessable via most data recovery software in the market today?


Yes. It will be safe from normal recovery tools.
December 20, 2007 2:08:00 PM

zenmaster said:
Yes. It will be safe from normal recovery tools.


With the data density on modern disks it's probably safe from anyone; but overwrite multiple times with 0, 255 and random values if you're paranoid. Took about ten minutes to write a C program to do that.
December 20, 2007 9:58:41 PM

Take a hammer to the printed circuit on the bottom of the drive.

No one will ever find it cost effective to recover the data.
a b G Storage
December 20, 2007 10:13:34 PM

Well considering the government spends millions on political campaign advertising, what is another couple of thousand for some data they really want?
December 20, 2007 10:34:23 PM

GeorgeH said:
Take a hammer to the printed circuit on the bottom of the drive.

No one will ever find it cost effective to recover the data.



Unless you robbed a bank and kept your check list, get away plans on the disk. :pfff: 

But they would likely see you viewed this page as they would contact THG for people logging in and out of the board.

There's not much you can do that doesn't track you in some way or another. :heink: 

Absolute best way is zero fill several times and deep six it somewhere... but zero filling takes a long friggin time. :sleep: 
a b G Storage
December 20, 2007 10:38:03 PM

^Thats why you use proxys and Linux :) 
December 20, 2007 11:18:27 PM

what you dpo is you unscrew wthe case off the disk, then you get an industrial electomagnet, wave it over it a few time and no-one will ever get any data back...
a b G Storage
December 20, 2007 11:20:12 PM

if u want ur data delete there is only one way to ensure its gone and completely unrecoverible. i served in the military and know first hand about this. you need the disk destroyed and when i say destroyed i have some specifics...first you need a super strong magnet or electomagnet....you need to place the magnet physically on all disks...think thats enough...well its not even that can be undone with the right tools. after your done demagnitzing the platters you need to either sand/sandblast them down at least a half milimeter and or use a welder on every square inch warping the disk and melting the platters. and of course if ur doing this to military/ govertment spec (for classified material)before you do any of what i said you have to reformat refill the drive entirely with "filler" data at least 15 times....think i am joking....i am not laughing. even than its possible to recover minute amounts of data. but its the best way there is...cousre down side is ur hdd is toast. all depends how bad u want to get rid of the data.
a b G Storage
December 20, 2007 11:27:21 PM

Send it to the sun, if the heat doesn't fix it up, gravity will. And I don't think even the military/government will bother trying to retrieve it from there.
December 20, 2007 11:37:36 PM

Writing over it with 0's once can still be recovered, even with some of the tools available to normal users now. It may be fractured, and unsorted, but you can still get info back.

I 2nd the Derik's Nuke and Boot, they have a couple different programs on there, including the DoD(Department of Defense) standards, as well as one even more aggressive. I believe it wipes and rewrites this disk like 27 times.

It takes a few hours.
December 21, 2007 12:56:26 AM

An industrial furnace cooking along at 2000F does a pretty good job of destroying most evidence. What is not destroyed is easily manipulated into something else. Good luck finding something on a sheet of metal that has been reshaped into a pretzel or a Borg cube.

Don't have an industrial furnace in your backyard? Well if your Aunt has a glass or ceramic kiln then you already have access to a furnace.
December 21, 2007 1:46:49 AM

Take the platters and mutilate them, if you have the capability, drill holes all over them, run industrial electromagnets over them and scatter the pieces. No one is going to get your data then.
December 21, 2007 1:49:07 AM

If you have access to them, a thermite grenade will do the trick ;) 
a b G Storage
December 21, 2007 3:01:32 AM

As ethel asked, what do you have on there that needs to be deleted that bad?
December 21, 2007 3:19:33 AM

to OP:
um.. you tryin' to sell your ol' hdd on ebay or somethin'?
if that's so, then don't
(not to mention some used hdds sold on ebay are not properly formatted at all...)

*walks away whistling*
a b G Storage
December 21, 2007 3:25:51 AM

what every u have thats so bad on ur disks u don't want to get caught with it. chances are the right computer foresentic tech will get some of the data no matter what unless the platters are utterly destroyed...and even then u may not be out of the woods. what ever that data is u don't want anymore...i wouldn't the jail sentance that would come with it, or wife/gf's wraith that comes with it.
December 21, 2007 3:40:23 AM

kittyhawk said:
I know of HDD utilities that can recover data that has been deleted from the recycle bin. Does zero filling a hard disk drive really make all data on it totally unrecoverable?


Define totally, and also mention if you want the drive to be usable afterwards.

If you want the drive usable you can't ever 'totally' remove the possibility of data recovery. The DOD method of wiping media is very effective in making it extremely(and I mean extremely difficult) to retrieve data. You'd need multi-million dollar pieces of equipment and a team of engineers to attempt to recover your data afterwards. However, if you need to protect some of the military's nuclear secrets then buying a new drive is safer(and required as complete destruction of the media is sometimes required).

If you need complete and total impossible data recovery destroy the drive.

Me personally, if I had some kind of data on my drive that I wanted to make sure nobody could possibly recover and I had intentions of giving it to a friend or family member, a DOD wipe is plenty safe for me. Generally speaking, nobody in their right mind is gonna spend countless hours and millions of dollars to attempt to recover your 'possible' data in an attempt to see if they caught you doing something illegal(or whatever you are trying to protect).

My piece of advice.. ALWAYS disconnect ALL drives you do not want erased. It would suck to accidentally chose the wrong one.
December 21, 2007 5:31:40 AM

Dooyas said:
Writing over it with 0's once can still be recovered, even with some of the tools available to normal users now. It may be fractured, and unsorted, but you can still get info back.


What are your sources on that information? I've seen no such tools. I've seen recovery companies say that even they cannot recover from a zero-filling
December 22, 2007 8:47:16 PM

Dooyas said:
Writing over it with 0's once can still be recovered, even with some of the tools available to normal users now. It may be fractured, and unsorted, but you can still get info back.


This is not true. If you use a program that overwrites every sector of the HD with zeros, no program will be able to recover anything through the HD interface. The only way to recover information off of a HD after a full overwrite would be to take the HD apart in a lab and use an electron microscope or microprobing techniques to reconstruct the data.

Your reference to the article at CNet is a prime example of many people talking who don't know what they're talking about. The original poster in that article used an overwrite program that only overwrote the file contents, but didn't overwrite the directory information on the drive. That's not a fault of the philosophy of erasure, that's just a poor erasing program.

Good erasing programs erase every sector of the disk. Programs like Darik's Boot and Nuke or Active@ Killdisk. If you erase a hard drive with one of those, no software will recover your data, period.

Different erasure methods can offer security from different kinds of government recovery techniques. A simple zero-fill (one pass) will be enough to make sure that no software can recover anything, but the CIA/NSA can take the drive apart in their labs and recover from a zero-fill pretty easily. With more overwrites, it becomes harder. The DoD 5220.22-M compliant method involves 3 overwrites - once with a fixed value, again with the bitwire complement of that value, and a 3rd time with random data. The US Government approves of the 5220.22-M method to erase classified data up to the secret level. This should tell you how difficult it becomes to retrieve data after multiple complementary overwrites.

An extended DoD 5220.22-M method involves doing that 3-pass overwrite method twice, with another pass of random data in between, for a total of 7 overwrites.

The Guttman method, which involves 35 passes, is generally regarded as so safe, it's equivalent to destroying the drive. However, no one knows this for sure, because if a government agency were able to recover data that was erased with Guttman, they sure wouldn't tell anyone. ;) 
December 23, 2007 8:53:34 AM

SomeJoe7777 is right. If the hard drive interface was capable of reading the 'overwritten' data, then the actual data would be corrupt. It is impossible for the interface to be capable of reading the 'overwritten' data.

Think about this too...

If you overwrite a zero with a zero, how is the interface supposed to know that the zero was overwritten with another zero? This is why engineers and serious technology has to come into play. They have to watch for the shifting of the data and attempt to asertain the slip of the data over time and then read the data before the slip.
December 23, 2007 9:24:22 AM

If your running Windows 2000 or XP Pro a free way to do is to select the folders you want to be deleted, right click on it go to properties>General Tab>Advanced>Tick Encrypt data then delete the folder.
December 23, 2007 9:42:46 AM

If I ever felt that I needed to do such a thing I would simply trick the ones who have something against me. Its very doubtful that they currently know your serial number on your hard drive. Buy the same exact one you have now and switch them. Install windows on it and a few other programs that any normal computer users use. This way they simply think you reformatted your hard drive and the data they desire is still somewhere on it. Which they will find to be a impossible task and would help to "prove" you to be innocent.

Now for your old hard drive this is up to you... you could hide it... you could give it to a trusted friend. or you could drop it to the bottom of the ocean if you really want. Guess it matters how important the data really is to you.

I don't want to know what is on your hard drive nor do I care. But if its something very bad and you know your currently being suspected of it then I advise you literally destroy it in a non populated area like in the woods and then bury it in several different places. Or if you came across something that isn't really bad but others simply don't want you to share then just release it on the internet somewhere other than your house (someone elses wireless internet connection on your laptop would be great) then repeat the destroy step above right after.
December 23, 2007 10:07:29 AM

One pound of thermite ignited on top of the hard drive will make the data completely non recoverable.
All other means of data wipe can be circumvented with time, PGP data encryption works better, but not as good as thermite.
a b G Storage
December 23, 2007 10:28:49 AM

For hard drives that I simply want to replace (ie throw away), I simply smash the hell out of it with a hammer several times leaving deep dents in the casing itself. I also destroy the circuit board as well and rip away the ribbon connecting the circuit board to the hard drive on the underside.

Great way to relieve stress while playing around with a hammer.
December 23, 2007 11:38:45 AM


Thank God for people like ... "SomeJoe7777" and "smitten" ...who actually know what they are talking about... and are giving good, sound advice.

To the rest of you... thank you for giving forums like this a good place for humor... everytime I need a good laugh... I come in here and read responses like these...I really can not stop laughing

Quote:
No.
The more times you do this the harder it is to retrieve the data.

If you do this a couple of times, you should be relatively safe.
However, the Gov't if it really wants to can do amazing things to get at the data.

Most ordinary hackers will not get past the 0 wiping.


LOLOLOLOL... oh my god ... LOLOLOLO... you are just to much!!!... what three, maybe four years of college... I can definately tell... LOLOLOLOLOLOL

Quote:
Absolute best way is zero fill several times and deep six it somewhere... but zero filling takes a long friggin time. :sleep: 


LOLOLOLOL... wait... lets do it a few more times ... just to make sure....LOLOLOLOLOL!!!

Please keep it up guys... way to funny!!!!

But to get serious with you...

.....

I'm sorry... I can't...

I'm still laughing way to much!!!

LOLOLOLOLOLOL

I'm going to go read some more of the "Funnies"... whoops...I'm sorry... I meant Forums in here at "Tom's Hardware".

LOLOLOLOLOL

"hiccup"
December 23, 2007 12:08:02 PM

Nice and productive contribution doggy. Talking about being a college boy?
December 23, 2007 1:13:29 PM

If you mean totally as in absolutely impossible to recover any data then the only way is to utterly destroy the drive. By either throw it into the gate of Oblivion, shove it into the Maledict's mouth or blast it with a BFG.



Ehem was joking, do what atomic said.
December 23, 2007 2:05:50 PM

aziraphale said:
Nice and productive contribution doggy. Talking about being a college boy?


PowerDOg really has no clue.
I don't think he knows that there are people with high-end data recovery equipment that can over-come zero-filled drives. Much like the data-recovery services to which you can send drives.

Now, what would be the point of some of hackers putting all this effort into data recovery?
Identity Theft. Stolen Passowrds. Account Information.

A single home user's HDD could be worth $10,000s and very easily $100,000s to one of the many professional organizations which are involved in such high-end criminal activity.

They often scour eBay and other places to try and find just such drives.

I recall listing on Laptop on eBay w/o a HDD because it died.

I was PM'd by multiple folks offering me more money for the dead HDD than a new one would have cost.

I wonder if the poster has such a high Zero-Filling requirement?
I wonder if he knows most large corporations have such requirements?

Or perhaps the poster is a Jr. High School kid who does not have anything more secret than his WoW account.
Or perhaps somebody who does not have any idea what is really hidden on his HDD.
December 23, 2007 2:20:15 PM

thuan said:
If you mean totally as in absolutely impossible to recover any data then the only way is to utterly destroy the drive.


That is correct. That's also why any overwrite method is not approved by the US Government for destroying Top Secret data. The drive must be destroyed physically.

You have to keep in mind that the protection you need to keep something secret is in direct proportion to the importance and/or time sensitivity of the data. For example, let's say the army has some information about combat tactical plans stored on a hard drive. But the plans it's talking about are going to happen in 4 hours. Well, what erasure method is good enough if you need to keep that data out of enemy hands? The answer is any method that would take the enemy longer than 4 hours to recover. A simple zero fill would suffice here, because the enemy couldn't get the hard drive into the lab and get the data reconstructed within 4 hours.

As far as importance, whatever information you have stored on your hard drive that you might want to keep secret (financial records, e-mails detailing the affair with your secret girlfriend, your MP3 collection, the pr0n collection, etc.) ... that information is likely not important enough for any government agency to bother taking your hard drive to the lab for recovery. It's much easier to get evidence against you from other sources. If the authorities were going to prosecute you for music sharing, for example, they don't need your MP3 collection. All they need to do is contact your ISP and get a record of all the torrents you've been connecting to and that will be totally sufficient in court. The fact that you erased your hard drive just incriminates you further by proving that you had something to hide.

In this day and age, records that detail your every move are stored somewhere that you don't control. The ISP has a wealth of information regarding your connection times, inbound and outbound connections, etc. The search engines have a record of all your searches. The e-mail servers have a record of every e-mail. The banks have a record of every transaction. And on top of this, the government is piping all Internet traffic through filters that are looking for terrorist activity, with the help of the ISPs. Those filters have a detailed record of everything. Believe me, if you are doing something illegal on your computer, there's enough evidence out there to prosecute you for it, and erasing your hard drive won't make a damn bit of difference.

Do yourself a favor - if you don't want to be in trouble, then stop doing illegal things. The authorities are slow to awaken, but once you've piqued their interest, you're phuqued. Darik's Boot and Nuke isn't going to save you, and in all likelihood, neither is your court-appointed lawyer. Believe me, the defendant's chair is an unhappy place to be.
June 2, 2012 11:57:11 PM

Right click and delete should do it. Also don't forget to empty your recycle bin. If you are a truly paranoid bugger then blow the damn thing up. Hire a tank or something. Or just scratch your monitor. When the cops are looking through it. They won't be able to see anything. Epic win.
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