

iPhone Takes Screenshots of Everything You Do - nreece
http://blog.wired.com/gadgets/2008/09/hacker-says-sec.html

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mikkom
They seem to be describing double-buffering.

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shutter
I have a question related to this:

I've heard a little about issues like this, where old data still exists even
though you thought you deleted it -- or it's still in RAM for instance. When I
read TrueCrypt's info, I seem to recall something about how your data is still
potentially visible to others unless you shut off your PC first (and then it
might still be retrievable?).

I'm not trying to hide anything, but I've always been curious as to what it
takes to _truly_ wipe all traces from a computer without physically smashing
the drive, for instance.

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a-priori
Just killing a process will leave its core intact in memory until the pages
are reused by the operating system. If the computer is then hibernated (and by
default Mac OS X writes hibernation data when you suspend it), a memory dump
is written to disk that may include this data. If a process was manipulating
sensitive data -- cleartext passwords, cryptographic keys, or so forth -- then
that data may be persisted even after a program is killed.

The good thing is that, as far as I know, most operating systems use a first-
in first-out page allocation algorithm. This means that newly-freed pages will
be given out first, so the life-span of this "zombie data" will probably be
short.

Also good news is that RAM is volatile by nature, so it doesn't store
"imprints" like hard drives may after a write. If a byte of RAM is
overwritten, all traces of the old data is gone within a few nanoseconds. This
means that if you are paranoid about this sort of data leak, you should zero
sensitive memory buffers before returning them to the system.

I know a bit about the analagous problems with hard drives, if you're
interested.

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otto
Though RAM is volatile it is possible to get data off of it. I've heard of
techniques of using extreme cold temperatures to slow the clearing of data.

I think there are papers on this referring to it as "Low temperature data
remanence"

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trezor
I actually _wanted_ to take screenshots on the iPhone the other day, and
wondered if there was any software which would allow me to do so without
jailbreaking it.

This sounds like a little bit too much work though :)

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simonw
Hold down the power button and hit the button on the front once - you'll get a
white flash and a screen shot will be saved to your photos folder.

~~~
derefr
Additionally, if you continue to hold down the front button, rather than just
pressing it, you'll perform a hard reset of the iPhone.

~~~
trezor
Voted up because the few times you actually need to hard reset an Apple
device, it's bloody far from obvious how you do it.

