Thoroughly destroy your data
- David Moore
- Feb 21, 2019
- 3 min read
Normally I preach about backups to anyone who’ll listen and also to a good many who don’t.
Sometimes the conversation swings to data recovery “yeah, but what if I don’t have a backup?” and how to get data back from the most unlikely of scenarios.
Well, not today. Today I am talking about how to thoroughly destroy your data so no-one ever sees it again.
As the life-cycle of our technology gets shorter the need to securely dispose of things that store our personal, private, valuable and compromising data increases.
If you aren’t careful then it is all too easy to simply let the most valuable and private information slip into the hands of... well... anyone.
The technologies that helped you get back that file you desperately needed when your computer crashed are the same ones that can get your file back when you give the computer to someone else.
It is often suggested to me that “I’ll smash my computer with a hammer”. That’s all well and good under certain circumstances. But do you really know where the data is stored on your computer? Hammering your computer into a non-functional state may not necessarily destroy the hard drive and, even if it does, have you checked to see just what sorts of damage data can be recovered from?
I suggest you pop along to CBL Data Recovery’s web site (http://www.cbldatarecovery.com.au) and peruse their hard drive recovery services and testimonials. You may be surprised at what can and has been recovered from “dead” computers.
So randomly smashing an otherwise perfectly functional computer just to erase your data is not a good idea.
The best way to securely erase your computer is to do it while it is still functioning and under your control. This also means you don’t have to physically destroy the drive and render good hardware useless.
“Secure erasing” software is fairly easy to come by in the freeware arena.
The ones I use most often are “Eraser” (funnily enough http://eraser.heidi.ie/) and Ccleaner (which includes a “Drive Wiper” function as part of its extensive tool set https://www.ccleaner.com/ ). These are Windows-based tools.
In the Apple world MacOS has secure erasing built in (depending on which version you have - http://support.apple.com/kb/HT3294).
There are also ways to remotely erase your computer if it gets into the wrong hands. Of course, the obvious limits to this are that the computer has to receive your erase command and the bad guy has to not notice the erase taking place. But it’s still worth having this capability in your toolbox.
You can also encrypt your hard drive while you are using it so that, if it ever goes astray, the contents can’t be seen by anyone who doesn’t have the encryption key. Encryption is kind of like “erasing before the event”.
These erasing tools work by overwriting “empty space” and selected files with useless random information. This means that when someone tries to recover the files all they get is rubbish.
These tools will work on pretty much any drive, USB thumb drive, or external hard disk you can plug into your computer.
You do need to know a few caveats though:
If there’s anything you want from the drive/computer then back it up before you start. Seriously.
Securely erasing a drive can take a very, very long time.
You need to check just what is being securely erased and that it corresponds with what you need protected. E.g. if you are erasing “blank space” your files should already have been manually deleted AND removed from your recycle bin etc.
If you make a mistake you can secure erase and kill the whole system (or you may do that intentionally).
There are various degrees of secure erasing depending on how hard you need the recovery of the data to be. Some clever folks can get past single and even multiple overwrites if they really want to.
Some devices, such as Solid State Drives or SSDs, have built in electronics that can confuse secure erasers and in fact prevent them from doing their job. Things look OK to you but tid-bits get left around the place without your knowledge. Make sure you get a proper SSD certified erase tool or procedure.
The important thing to take from this is that you need to do this before you give away or sell any old computer.
No matter how long you try to hang on to an old computer, sooner or later you’ll want to get rid of it and you’ll have to address this issue.
Sledgehammer anyone?
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