Selling PCs--advice for cleaning HDDs?

I've got a really old (ca. '98) Compaq Presario desktop and a less old but still wheezy Compaq Presario notebook that I'm planning to sell.

I've pulled off all the files I want and deleted them, but I'd like to be sure that whoever buys the computers can't recover data (passwords, account numbers, etc.) In short, I'd like to get everything off the hard drive except the OS (Windows98 on the dt; Windows XP on the nb).

What's the recommended software or method for this?

I have no idea where the recovery/OS CD that came with the desktop is now. I do have the WindowsXP disk for the laptop.

 

Are the hard drives really even worth anything? Why not pull them out and destroy them?

If that's too drastic, you may want to try a shredding program--once you "delete" a file, it's not really gone; the MBR record is erased (the "address of the data"), but the file is still there. That's how people can recover hard disks.

 

http://dban.sourceforge.net/

 

You nee to understand that by simply eliminating the partition or formatting in many cases, you are simply destruying the index but leaving all the info there.

Think of it as a book with the first page (index) ripped out...The rest is still there.

 

obviously nothing nothing is completely safe unless you put it through a furnace, but dban aint so bad for the for the majority of us who dont need to shread our garbage because we dont feel that constant fine tooth comb over our heads

 

Personally, i'd zero the drive with either free tools or the disk diagnostic software, and include the restore disk.

 

Yup, like dave said. Just zero the harddrive, depending on how many passes and size of harddrive it can take a few hours until all day.

 

Re-install the OS and format the drive

 

formating and rewritting it a couple of times should make the date very hard if not impossible to find in a accesable form

 

Tossing the drive to melt in a fire is might be the ultimate way to destroy it, but then you'd have to burn it for a while and deal with toxic fumes

 

Use DOD 5220.22-M compliant technology. 100% privacy safe. DoD 5220.22-M prescribes overwriting data in 7 passes This will write ones and zeros to the drive.... do a google for "DOD 5220.22-M"

 

http://www.heidi.ie/eraser/

Check that one out, it has the full DoD (department of defense) specification. It even goes a little higher and gives you an insane amount of rewrite ability. If you want to provide the default OS on the system, and you have the installation CD. Then you will want to wipe the entire drive..... you can't do this if you are booted up on that hard drive though.

So if you can take the HD out and put it in a 2nd machine that has the eraser tool on it that is the way to go. then you will want to just right click on the disk and click 'erase', it will give you a little dialog and you can select the rewriting method. You can get more advanced and create your own method. The DoD requires 7 times rewrite, as after 7 times it is generally shown that it is impossible to reconstruct. A researcher found that it is still possible after 7 times, and there is a paper where he advocates a 35 time process. you can read this on the site above, the author of the paper is Gutmann, and this tool was primarily created to be a light weight, opensource, free tool to implement the best erasing algorithms.

It is very easy to use, and 4-5 times is plenty if you want to feel secure. If you are an elite spy you may want to move up to 7+, but if I am telling you that, you won't be an elite spy for long!



Option 2)
you don't want to take the HD out of the case, but you want to remove all of the stuff on the HD.
1) delete everything you can on the hard drive, all programs, files, etc, everything windows will let you expect eraser
2) Use eraser to erase the 'empty space' on the hd
3) Reinstall the OS using the recovery disk
4) use eraser to erase the 'empty space'

That isn't perfect, but unless they are die hard to find out about you they will not be able to.

Remember when doing secure removal (shredding is a common term), that it can take a long time. It will force the HD to write junk across all the space you want to erase, and it will do this however many times you want. So if you plan to erase a 60GB hard drive, expect it to take hours. It is going to have to write 60GB, 7 times if you use the DoD standard, and then you add in processing time + operating system time, and you can easily have it go for a long time.


If I were you I would go with option 2, just erase your free space before you reinstall the OS (if you can), if you can't reinstall the OS, then erase the free space, defragment, and erase the free space again. What you want to do in the case where you can't reinstall the OS, is to cause those files to be physically moved on the disk which defragmenting will do somewhat

Cheers.

 

If you want to zero the drive more than once, you're better off vaporizing the drive.

 

Just to muddy the waters further, I have had forensic computer experts tell me they have recovered useable data from drives which were supposedly run through cleaning programs double digit times.

The only way to be 100% certain is physical destruction of the drive.

The question I can't answer is how much certainty do the other methods give.

 

My view is:

If someone really wants to get into your computer, hack your identity, recover stuff from your disks, etc.......... they will. On the other hand, the average joe doesn't really care and if anything they may have a program that will recover erased data (Norton, Macafee, xxx), those programs won't recover anything with 2-3 passes (if they can get things with 1 pass they are doing good).


Just hope you are selling to a normal person, because nothing you can do will ultimately stop a hacker.(save for not selling them the drive)