Disposing of your computer
Data removal is a critical issue for anyone who is disposing of a computer, - from home computer users and business people, to community organisations and businesses. Whether you are purchasing a new computer, upgrading to a newer faster model with more capacity, or just replacing your computer's hard disk, it is wise to be careful about the disposal of your hard disk.
All your information, everything you have done on your computer, has been stored on your hard disk and is most likely retrievable. Everything you ever put on the computer - even if you didn't save items, or if you deleted them after use, still exists on the hard disk. Residual data can compromise the confidentiality of personal and financial information and could lead to all sorts of identity theft, fraud, extortion etc.
Pressing the DELETE key does not mean that the information has vanished from the computer; it is not the equivalent of shredding paper files or burning them. When a file is deleted, your computer hides the link from that piece of data to the folder, but the data still remains. Emptying the recycle bin on your desktop does not remove the data either.
Today's analysis tools can retrieve data from 15 year old hard disks, from hard disks which have been run over, dropped in the ocean and supposedly cleaned by non effective software applications.
Research into second hand hard drive
There have been a number of research findings which report that a large number of second hand hard drives contain significant volumes of previous owners' sensitive information which can be retrieved.
Simson Garfinkel began research in 1998 for one part of his Ph.D. thesis. He purchased over 200 second hand hard disks from second hand shops and from eBay. He designed analysis tools, and used them on these disks to see what information remained. He found large amounts of sensitive information; only 11 hard disks were 'clean'., Included in his findings were people's credit card numbers, detailed financial records of organizations, patients' medical records, corporate trade secrets and other highly personal information.
Garfinkel went one step further in his research and contacted as many of the disk owners as he could to figure out why so many disks still contained data. Two problems he identified were that:
- some people did not think about what happened when they disposed of the disks (Garfinkel calls this the "education problem")
- many applications lie when they tell the user that their data is being removed (Garfinkel calls this the "usability problem").
What can you do about your old hard drive?
NetSafe recommends that anyone wishing to dispose of a computer, use a device or software that is specifically designed to erase information. Reputable forensics companies can also 'clean' your hard disk.
The most reliable method of dealing with your old hard drive is to remove it and destroy it by compromising its physical integrity (by drilling numerous holes in the hard drive or putting it into a blast furnace).
Regardless of how you decide to clear your hard drive, do ensure that you undertake the most rigorous processes before recycling your hard disk, or passing it to a friend or family member, or dumping it. If you don't, that decision could come back to haunt you.
Information on the Ministry of Education's approved recyclers can be found on the Computer Access NZ Trust website (www.canz.org.nz).
NB. Don't forget to transfer all your files and information to another storage device before you dispose of your hard drive.
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