Data on old hard drives

http://www.bbc.co.uk/news/technology-17827562

Watchdog finds undeleted data on second-hand disk drives

Of the 200 hard disks collected, 11% contained personal information.

At least two of the drives had enough information to enable someone to steal the former owners' identities, the watchdog said.

I'm slightly peturbed at that statistic. Why didn't they say three drives or the actual amount? "At least two" is a strange way of putting it when dealing with whole numbers.

Equally they didn't add that many buyers of second hand drives are not looking for peoples' data, however, the article might encourage some to start looking or worse, start buying to get data.

Lastly the Beeb article doesn't give advice on how to delete sensitive data from their drives. Here are a couple of free and easy methods:

1) If just throwing the drive out, delete data, format drive, then take it apart and smash the disc(s) with a hammer. Best to do this in an area where it can catch all the shards of glass. Data definitely gone!

2) If selling on, delete the data, and copy useless data to the drive until full. Download a large file and copy it or copy the copies. delete data with a free drive wiper program, such as the one which comes with CCleaner. Then format the drive. Data gone!

Personally, I never sell on my HDDs, so I use option 1, but also do the files and CCleaner bit too. Overkill is impossible when dealing with your data.

Edited by camieabz (Wed 25-Apr-12 11:37:41)

Yep, even overwritten files can be retrieved - best to do a full reformat or if the drive is not working smash the disc with a hammer!

In reply to a post by 4M2:

Yep, even overwritten files can be retrieved ...

By who? I thought this had the status of an urban myth.

In reply to a post by john2007:

In reply to a post by 4M2:

Yep, even overwritten files can be retrieved ...

By who? I thought this had the status of an urban myth.

It is possible but the techniques used are time-consuming and require specialist equipment. At the most extreme, magnetic ink can be applied to recording surfaces and the patterns read using a microscope.

With today's paranoid government agencies the very act of physically smashing a hard drive to prevent data recovery is enough to invite their closest scrutiny.

If the police or said agencies were forcing an entry to a property and discovered someone in the act of doing that, fair enough. Otherwise, it's a sensible precaution. No different to shredding sensitive mail.

http://en.wikipedia.org/wiki/Data_recovery (section titled overwritten data).

SSDs may be more of a risk.

Most of the used drives that I come across have all the data fully intact. What surprises me is that the percentage is as low as it is!

My info is several decades old. I used to know someone who made colloidal magnetic suspensions for researchers and forensic organisations. Of course, magnetic force microscopes weren't invented then and the amount of data recorded on disk drives was miniscule compared with today's devices.

I've only given the article a quick scan but it does not seem to mention bad blocks that have been reassigned by a device's internal firmware. These will be invisible to standard software but will be visible to specialist hardware and may contain useful information.

The best security practices are (1) use of drive encryption in case of theft and (2) use of a sledgehammer prior to disposal.

Edited by micksharpe (Wed 25-Apr-12 15:50:03)

In reply to a post by john2007:

In reply to a post by 4M2:

Yep, even overwritten files can be retrieved ...

By who? I thought this had the status of an urban myth.

It can be done if you're really determined, but as Mick said it's expensive and time-consuming.

But if the data is worth it... when we had to dispose of classified HDDs at Aldermaston, they were stripped down and the magnetic coating sandblasted off the platters.

edit- and two witnesses had to sign off that it had been done properly!

Edited by billford (Wed 25-Apr-12 16:35:36)