Those Files You Think You Deleted?
Still on the hard drive, folks. From The Telegraph:
Which? Computing bought eight second-hand hard drives from auction site eBay and found that they still held information that could be confidential. Using free software downloaded from the internet, the computer magazine said it was easily able to recover 22,000 ‘deleted’ files, including images, music files and spreadsheets.
Cifas, the fraud prevention service, says it recorded 77, 5000 cases of identity fraud in 2007.
Dr Richard Clayton, from Cambridge University’s computer laboratory, explained that erasing data from computers is not as simple as deleting the files.
“The way the operating system works is that even when you think you have deleted a file, it has just removed the file from the list directory. However the data remains on the computer,” he said.”
Frankly, most people have absolutely no idea how the computer they are using actually works. “Deleting” a file actually does no such thing. The data is still all there. The operating system just pretends it isn’t there. Personally, I have never sold a computer or a hard drive, I use them until they drop dead, then dispose of them. But I always use a program called Darik’s Boot And Nuke (DBAN) when I reuse a drive in a new computer or have to reinstall an operating system into an old one.
Please note that DBAN is a drive killer, so to speak. It wipes the entire disk completely and does so with great enthusiam. There are several levels of drive wipe in the program, some take a very long time to run. (Highly recommended if your drive was infected with something but you want to reuse it.)
If you do not wish to erase your drive completely, this program, Heide Eraser, can just wipe the files you want gone, not the rest of the disk. (Hihgly rated, but use at your own risk, of course.)
But if you really want data gone, with no chance of recovery, the only choice is to destroy the hard disk completely.
Geek Stuff | Gaius January 7, 2009
By tarpon, January 7, 2009 @ 7:16 pm
Programs named ’shred’ and ‘wipe’ work for us Linux/UNIX users.
You are right about most users think that delete means delete when it simply means remove file’s entry in the allocated blocks information.
By Gaius, January 7, 2009 @ 7:24 pm
Yeah, the programs mentioned in the post are for Windows machines.
By MikeO, January 8, 2009 @ 10:31 am
In my first job out of school, I worked on systems that processed classified information. All magnetic storage media, including DASD platters, were destroyed when decommissioned. We’d box the stuff, call for pick-up, and it would be taken to be burned in an incinerator.
I have a box with every hard drive I’ve ever owned. The oldest one is a 20MB MFM drive I bought in 1986. I advise people to pull and keep their hard drives when disposing of computers.
If you want to recycle a computer through donation or as a gift, either send it with no drive, or buy a new hard drive for it. So long as what you buy is well below the extreme size/speed limits of the day, hard drives are much cheaper than risking information exposure.
One of these days I’ll look into finding incineration services, or I’ll pull them apart and shatter the platters. Or, if I can find an outdoor range that allows it, I’ll take them out and shoot them.
By sam, January 8, 2009 @ 12:34 pm
I have used disk sanitizer software to wipe hard disks that were removed from service when the PCs were upgraded. This particular version of disk sanitizer software let you pick the degree of sanitation. The level I used would overwrite the entire disk with random 1s and 0s seven times. As I recall, it took an hour or two for each disk. We don’t deal with anything confidential where I work, though.
By Sylvia, January 8, 2009 @ 4:06 pm
We pop hard drives we think we might want to use again into external enclosures, label well, and store. If it’s certain we won’t use the thing again, I favor a sledgehammer and safety goggles. My FIL just rigged a series of old computers to access data on an old drive and step it up through the various operating systems for us.