Yesterday, at work, I said goodbye to an old friend.
I formatted my laptop.
It’s not completely gone, not yet. Before formatting, I converted it to a virtual machine. I’ve got my Acer Aspire netbook hooked up at work and, using an external monitor, mouse, and keyboard, I’m now connected to the virtual version of my old laptop. That way I can still work while my old hard drive is wiped over the next couple of days.
Couple of days? Yes, I’m doing a seven-layer DOD (Department of Defense) wipe of my laptop’s hard drive using DBAN (Darik’s Boot and Nuke, a free program). Doing a quick format of a hard drive is kind of like tearing the table of contents out of a book; all the information’s still there, and all you did was make it a little harder to access. (Believe me, plenty of free tools can retrieve your files instantly.) A full format isn’t much better — again, there are many available tools that can recover 99% of data lost from a full format.
As you may or may not know, computers store information in binary — 1’s and 0’s. The safest software method to truly wipe a drive is to not just format it, but cover the entire drive with either 1’s or 0’s. The average person or company can not retrieve information from a drive wiped using that method, because all the information has been written over. Theoretically however, it is still possible. Using forensics, it may be possible to determine how long a 1 has been a 1 (or a 0 has been a 0). With that information, all the new 1’s could be changed back to 0’s, and your information could be retrieved. (If you’re dreaming of trying this at home, don’t bother — you’ll need some high tech equipment and software worth tens of thousands of dollars.) The DOD standard, therefore, is (or at least was) three passes of wiping — that is, covering a drive with 1’s, then 0’s, then 1’s again. The next step up is a seven-layer wipe, which is what I’m doing to my laptop. Why? Because I can, because I’m into security, and because it’s not every day you can take a working laptop, set it aside for several days and do things like wipe the hard drive seven times in a row to see how long it takes.
By the way, as of 2007, the DOD no longer wipes their old hard drives — they shred them.
At home solutions include hammers and firearms, among other techniques.
At work our standard HDD cleaning tool is a 3-pass BC Wipe, but we also have access to DBAN if we need it. BC Wipe is also nice because along with full disk-wipes it can just wipe empty space on an active volume while leaving the volume intact.
I forgot all about BC Wipe — I haven’t used that in ages. It’s a really good one too. I also should have mentioned Killdisk, which I used to use a lot. It’s much quicker than DBAN but not quite as thorough. It’s good enough for hard drives you’re selling on eBay, but not good enough if you’re trying to hide data from the NSA.
If you are trying to hide stuff from the NSA, I would recommend driving a large metal spike through the HDD with a 8 lbs sledge, then tossing it into a large fire for a while, then running over it with a steam roller, and then burying the remains with Jimmy Hoffa. That should just about handle it effectively.
I use Killdisk for the most part when I reformat my laptop, but I use DBAN when I reformat computers for an employer or my last day on a job somewhere so that my pron collection is not found.
I just line the bottom of the litterbox with my old drives. Theoretically, it’s not doing a thing to the data, but who the hell’s gonna want a bunch of old drives that smell like that? And sticky too. I can’t really oversell the sticky factor. Your cat could be a vital part of your data security plan.
Hell, I don’t even wipe my drives before I sell them on eBay. I think it adds some nice value to leave all that pr0n on there for them. (:
So far I’m liking the cat litter idea.
I bought some computers off of Craigslist one time and they were full of Naval (“guys on boats”, not “belly button) information, including spreadsheets with employee information and SSN’s. I tried a couple of times to call and let them know but they made it so difficult that I ended up just reformatting it and forgetting about it.
If I was trying to make sure that the NSA could not read them there is always thermite.
At the University we use DBAN all the time. At the Police Station we have a different method, our Police Hard Drives get to meet a friend called Mr. Sledgehammer.
The ‘correct DOD procedure for hard drives with heavy secrets’ I heard was:
1. do the normal disk wiping procedures
2. use thermite, and enough to make it a lot harder to recognize as a harddrive (unlike the video above) also because high temperatures rearrange magnetic information
3. send the remaining lump of metal to a landfill with guards
at work we use DBAN, sometimes as a fully automatic network-booting image