Erasing Computer Files

[flipstress]

Before donating or recycling old computers, how does one make sure that all the files are erased?

I thought just reformatting would do the job, but I googled and found that it's not enough.  According to http://www.us-cert.gov/cas/tips/ST05-011.html
Reformatting your hard drive or CD may superficially delete the files, but the information is still buried somewhere. Unless those areas of the disk are effectively overwritten with new content, it is still possible that knowledgeable attackers may be able to access the information.  

I also found out that commercial software packages are available that are supposed to erase files.  Does anyone have recommendations on the effectiveness of any of these or any other product they've used?
http://www.whitecanyon.com/secureclean-clean-hard-drive.php
http://www.whitecanyon.com/wipedrive-erase-hard-drive.php
http://www.aevita.com/trackseraser/

One tech forum asked the question if files can really be erased.  One of the respondents said that the entire hard drive has to be rewritten over with characters, while others say they just destroy the hard drive depending on their level of paranoia and the sensitivity of the data:
http://www.tek-tips.com/viewthread.cfm?qid=1085424&page=1

Thanks for any suggestion, comment, or rec.

 

[Nords]

Thanks for any suggestion, comment, or rec.

I yank the hard drive from the machine and give my kid a guided tour while field-stripping it to demonstrate its individual components. ("When you put your Pepsi can on top of the case, this is what could happen." "When you hear that noise, this is what's being damaged.")

Then we cut the platters up with tin snips.

I suppose a more frugal approach would be to put the old drive in a new machine as a data backup. But that opens up a host of power supply, data transfer speed, and OS issues.

 

[SteveR]

Nords,
I like that one. Nothing like a field demonstration to impress a young mind.

I did this with the installation of a floppy drive once. I had to explain that all electronic componets run on smoke. If you let the smoke out, it stops working.
:

My son still reminds me of this "demonstration" from time to time. He works for the IT department at the local University and knows all about smoke now.

 

[Marshac]

Simple- remove and destroy the hard drive. That's what we do with servers.... a little HDD bowling never hurt anyone.

If you're looking for a little less destruction, find a utility that will overwrite the disk sectors multiple times with random data- I believe Mil. specs call for 7 passes using complimentary data (ie: one pass of 010, and a second of 101) when drive destruction isn't required. There are freely downloadable utilities that can do this (from a boot disk of course)... I have some on disks sitting behind me (they're all labeled with big red letters 'DANGER! NOT A NORMAL BOOT DISK'), but I can't recall the name of the program off the top of my head. If you want to simply delete individual files, download the PGP encryption package- there is a utility that comes with PGP that will erase data AND overwrite the disk sectors that once contained the data.

 

[Marshac]

I did this with the installation of a floppy drive once.  I had to explain that all electronic componets run on smoke.  If you let the smoke out, it stops working.

I have seen this acrid (and probably carcinogenic) magic smoke before... usually escaping from RAM chips

 

[riskadverse]

Just do a full format (/u) on it from a boot floppy or cd. Nobody but a super wizard would be able to recover anything after that. You have to ask yourself why would a super wizard be interested in anything you have on that disk.
The truely paranoid format them three times, write to them multiple times and then destroy them. The biggest exposure is usually backup tapes and cd's left unlocked or even thrown away.

 

[maddythebeagle]

There is shareware/trials for this. Check out Cnet. http://reviews.cnet.com/4520-3513_7-6245517.html. but I like the reformatting a couple of times, but I think these programs are easier since you tell how many times to write over and you can just let it run. You probably dont want to destroy the hd, if you want to give away. Maybe it is too old anyway and bound for recycling. In that case....

 

[flipstress]

Muchas gracias for the responses, everyone.

The question was from a friend who was worried about financial data on her computer.  I will pass the info on and she can decide what she wants to do.  I think the shareware will appeal to her--thanks for the link, maddy.

It's good for me to learn this stuff, too.

 

[cube_rat]

I've toyed around with computer forensics and there are many superior tools out there that can recover a formatted hard drive. Also, the tools can most certainly recover hard drives that someone has tried to scramble.

I would go with Marshac and Nords: Remove hard drive and toss into the fireplace; heat until fully melted down to a useless blob. 8)

 

[SteveR]

I've toyed around with computer forensics and there are many superior tools out there that can recover a formatted hard drive.  Also, the tools can most certainly recover hard drives that someone has tried to scramble.

I would go with Marshac and Nords: Remove hard drive and toss into the fireplace; heat until fully melted down to a useless blob.  8)

You people must have Top Security information on your computers. Do you really think that someone is going to go to the trouble to find, descramble and extract data from your personal computer? I sure don't. I am sitting on 3 very old laptops (long story) and two desktops that are no longer being used nor wanted. I just don't have the time to deal with them in an environmentally friendly way yet. But they are on my list of things to do someday. For now two of them are just running Seti programs for fun and to give them a little exercise.

I will find a nice quiet spot under a nice tree and bury them I guess. I am just not into cremation.

 

[Marshac]

You people must have Top Security information on your computers.  Do you really think that someone is going to go to the trouble to find, descramble and extract data from your personal computer? 

Descrabmle? Unless you're using an encrypted filesystem (which NTFS supports- hint hint WinXP Pro users), you can just read the data off the patters. People buy used HDDs on ebay all the time for the purposes of identity theft.

 

[cube_rat]

You people must have Top Security information on your computers.  Do you really think that someone is going to go to the trouble to find, descramble and extract data from your personal computer?  I sure don't.  I am sitting on 3 very old laptops (long story) and two desktops that are no longer being used nor wanted.  I just don't have the time to deal with them in an environmentally friendly way yet.   But they are on my list of things to do someday.  For now two of them are just running Seti programs for fun and to give them a little exercise.    

I will find a nice quiet spot under a nice tree and bury them I guess.  I am just not into cremation.

You'd be surprised of the crap that can be recovered from your hard drive.  Yes, my cremation method is a bit much.  I was only illustrating the point to never think reformatting or running eraser type programs will prevent any type of recovery.  The tools I'm referring can be obtained pretty easily for those amatuer forensic types 

 

[BigMoneyJim]

There's a free program called shred available with many linux distributions. For work PCs I boot up a KNOPPIX CD and run shred /dev/hda . It overwrites 25 times by default I think, but you can set different options. It's a bit scary how it goes and does its thing without question. I usually let it run a few hours and am satisifed for my purposes; I'm not sure how long it takes if you let it run to completion.

It should be possible to make a boot disk that uses shred on various hard drives (the example I typed generally wipes the first IDE/ATA hard drive) without needing to know what you're doing, but I don't know offhand if someone offers one.

 

[BigMoneyJim]

Sorry about the double-post, but I tried a google search for (gnu shred boot disk) and came up with an article more thoroughly describing how to use shred and a free boot disk/CD for erasing hard drives.

 

[Cut-Throat]

What's really funny about this discussion, is that identity theft usually is pretty lo-tech. A low paid bank employee merely writes down your SS no., date of birth, account number etc. etc.

One identity theft ring was actually placing employees in these low level banking positions and paying them commission for every person info that they stole.

Erasing hard drive info discussions, are mostly academic.

 

[laurence]

BC Wipe

http://www.jetico.com/

7 times pass will ensure your data is unrecoverable except for methods far too expensive for anyone in the private sector. Marshac and BigMoneyJim are spot on as well. I have a tool that allows me to recover all data on a drive that has been formatted with a boot disc in about, oh, 90 seconds, once I aquire the image (that time period varies depending on the size of the drive).

 

[farmerEd]

You people must have Top Security information on your computers.  Do you really think that someone is going to go to the trouble to find, descramble and extract data from your personal computer?  I sure don't. 

Do you really think some kind a thousand miles away is going to take the time and try to hack his way into your personal computer over the internet and steal personal info?...oh yea, they do...that maybe why my firewall blocks close to 1000 hits per month from people "just testing" to see if they can get in...I have all kinds of personal info on my conmputers, that I wouldn't want to fall into some unknown persons hands...no matter how unlikely. When I have a computer to get rid of, I yank the hard disks, crack the seal on the platters and then let them soak in a bucket of rusty/muddy/oily water for 18 months or so...then I wrap them up in a plastic bag and throw them out with the household trash.

 

[BigMoneyJim]

Let me flip this thread around if I may. I have a dead hard drive at work (not mine). Is there any software that can read from a drive that isn't recognized by BIOS or Linux? I'm assuming the answer is no, but thought I'd ask anyway.

This isn't worth taking to a data recovery specialist. (Although if the drive can be read from the PC I'm pretty good at recovering data myself.)

 

[Marshac]

Let me flip this thread around if I may. I have a dead hard drive at work (not mine). Is there any software that can read from a drive that isn't recognized by BIOS or Linux? I'm assuming the answer is no, but thought I'd ask anyway.

None that I know of. If you have an identical drive, you can remove the PCBs (printed circuit board) from the dead drive, and replace them with with the working drive's guts. As crazy as it sounds, I have read stories about people doing this, and actually being able to retrieve their data.

 

[riskadverse]

None that I know of. If you have an identical drive, you can remove the PCBs (printed circuit board) from the dead drive, and replace them with with the working drive's guts. As crazy as it sounds, I have read stories about people doing this, and actually being able to retrieve their data.

Replacing the PCB has worked for me in the past.  Another trick is to put the drive in a freezer for a half an hour or so.  Be prepared to dump the data when you put it back in the computer because you'll only get one shot using this method.