Secure Hard Disk Erase

When a hard disk dies the main priorities are to ensure that there has been little or no data loss and getting the effected system(s) back up and running. The faulty drive is removed and placed to one side. What happens to this drive next? Is it casually discarded, finding its way into the nearest bin?

Dropping a faulty drive into the bin could be one of the most costly mistakes you ever make. Hard disks contain an extensive amount of information about our digital lives, photos, email, contact details of family and friends, banking and financial information and other documents you might not want others to poses. But the drive you have thrown away is faulty, who is going to want a faulty drive? Criminals, thats who.

The information that you leave on a drive could allow criminals to apply for official documents in your name, effectively stealing your identity. This could cause you all sorts of problems further down the line, I'm not going to go into further details just understand that you want to make sure your data doesn't get into the wrong hands.

So how can the data on a drive be destroyed? There are quite a few methods but the ones available to the general public are probably of most interest.


Method 1: Darik's Boot & Nuke

http://dban.sourceforge.net/

This application boots from a CD/USB Stick and will allow you to erase your hard drives by writing data over the surface many times. See the homepage for more details. This method should provide an erase secure enough for general use. Even if somebody tries to use recovery software to read the disk it will not find anything useful.

Method 2: Remove the Drive Platters

Take a screwdriver to your drive and open it up. Inside there will be a few round silver discs. These are the platters that hold your data. By opening the drive you have already broken the seal and have allowed dust inside. If you were to reassemble the drive the presence of the dust would cause scratches on the platters making them slightly unreadable in places. Removing the platters completely and physically destroying them (maybe with a hammer, remember to wear goggles!!!) will put the data beyond normal methods of recovery. An electron microscope could in theory read the magnetic domains off of the platter fragments and peice the data back together. Unless you are working on something highly classified nobody of sane mind will bother trying.

Method 3: Standard Erase & Damage

A 'Full Format' of a drive with your operating system should write zeros to the entire drive. This is the minimum you should do to remove your data. The next step in this method is to destroy the circuit board on the underside of the drive. The circuit board is usually common to only a series of drives. Whilst it may be possible to use an identical drive board to read the data it is unlikely somebody would try.

So I have mentioned 3 methods of drive destruction. The choice of which method(s) to use really depends on the state of the drive. A drive which still spins and can have data read & written can be erased. If the drive is completely dead its down to Method 2 and the board destruction of Method 3. Where possible all 3 methods should be used, use the OS to erase the data, then use Darik's Boot & Nuke to make sure its erased, remove and destroy the platters and then destroy the circuit board. If anybody tries to recover any data after all that they are welcome to anything they can recover.

5 Replies to “Secure Hard Disk Erase”

  1. When’s the last time someone rooted through your bin, found a damaged hard disk and suceeded in getting it working again, let alone managed to get useful data of off a formatted disk.

    I find it difficult to believe these mythical cyber criminal gangs are spending the time attempting to reconstitute formatted hard disks. Once the file table is rewritten the cluster order of most files will be difficult to determine. In FAT32 for example, the directory entries for the files will only contain the location of the file’s first cluster, the location of the rest of the file must be determined from the FAT. Given the size of modern hard disks, reconstituting data without the file table is a waste of time.

    On the other hand, hard disk platters make excellent coasters.

  2. Ever heard of defrag! Just delete your high security risk files and defragment your computer… simple if you think about what’s intailed in the defragment process!

  3. Ever heard of defrag! Just delete your high security risk files and defragment your computer… simple if you think about what’s intailed in the defragment process!

  4. Defragmenting is a file system level operation. It is there to tidy and optimise the data that is there. In the process of sorting things out some deleted data may get over written but there will be a lot of free space that wont be.

    The whole data area of the drive needs to be written over several times to remove recoverable data fragments.

  5. So wouldn’t it be common sense to simply fill the harddrive (up to the maximum defrag allowance) with low-security risk data and THEN defragment multiple times.

    That way there is no space left to store old file information… simple.

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