Could a technician discover my browsing history from seven years ago?

In this excerpt from
Answercast #62, I look at the possibilities of technicians finding old
information on a computer while they are attempting to repair it.

Recovering history

Let’s see. First, let’s start with the seven years part. It’s really
unlikely, but I have to say it is possible.

The way that files are laid out on disk… Well, it’s kind-of, sort-of random,
but the operating system tries to keep them really close together.

So, here’s a scenario that could result in history from seven years ago still
being available (at least on the hard disk) today:

• You have a very full hard disk.

• You do some browsing that creates some history. We’ll think of it as history
  that’s say out on the edge of your hard disk space.

• Now, you delete something on your hard disk that’s really big, so your hard
  disk now has a lot of free space.

• And while you’re at it, you delete that history, so that file that contained
  the history is now a deleted file.

We all know that means the file data is still on the hard drive,
but the sectors that it is contained in are marked as “available for use.” Like I
said, we’ve deleted a bunch of information from the hard drive, so it has a
bunch more free space.

In the subsequent seven years, that drive never, ever gets that full again.
You end up using it, you end up deleting files, whatever. But the fact is that
the disk never gets so full that it actually overwrites those history sectors,
those sectors containing your history from seven years ago. It’s possible.

I don’t think it’s very common. I think that by and large there are a number
of factors that play into this that effectively will cause most sectors to be
overwritten eventually. But the fact remains, we have to say that it is
theoretically possible.

We really don’t know exactly how likely it is because there are so many
factors at play here. The most important one of course being how much you use
your hard disk.

Secure delete

The only way to make that go away is to before you hand your
machine over to a technician, run a secure delete program that will delete or
overwrite all of the free space. That makes this kind of thing a non-issue.

That overwrites the data that was contained in those seven-year-old files
because those files were deleted, but the sectors still have the data. A free
space wipe actually goes through and overwrites all of the unused space on your
hard drive, so that there’s nothing that can be found anymore.

Nosy technicians

Now, how likely is it that a technician would find this stuff? Well, it
really depends on what the technician is doing.

They could be needing to look at deleted files in order to repair whatever
it is they’re repairing. They certainly could stumble across whatever this file
contains.

How likely is it that they are going to be specifically looking? Gosh, I
hope not very likely!

I mean, a technician should be sticking to his job. Hopefully, a technician (a good technician) is going to be busy enough that he’s going to be in, fix the
problem, and out. He’s not going to go spelunking on your hard drive for things
that he shouldn’t really be looking for.

On the other hand, we do hear it about from time to time. There are
technicians that discover all sorts of random things on hard drives, whether
that be because they’re actively looking (especially if they’re actively
looking) at deleted files.

That’s a pretty nosy technician, if you ask me. If they’re looking at deleted
files and that’s not part of whatever it is they’re trying to recover, that to
me is unethical and not a technician that I would want to use. On the other
hand, like I said, they could stumble across it. It is possible.