[HacktionLab] wiping phones data

[Cat]

Hey

Having had recent experience of trying to sanitise a phone (Galaxy 8, stock
Android), I have a couple of comments:

1) 'Factory reset' used to be much more obviously one setting, to the
extent that I'm not sure a non-tech-professional would be able to do it
effectively now. I wasn't able to find any setting that I was confident
would perform this for me, although I was using a Samsung Bloatware
Special. Your best bet seems to be to ensure all apps have been removed as
they do delete a lot of files as they go BUT see below for caveats.

2) Both Signal and WhatsApp (and others) are bad for keeping copies of
images sent to others. A neighbour kindly lent me a handset for a short
time and so I deleted and re-installed both of these apps, and deleted
everything that had been in the picture gallery. However, when I was
handing the phone back I plugged it into a Linux box and realised that even
deleting and re-installing had left a lot of stuff behind. There were
hidden folders containing thumbnails of images that were definitely not
mine and definitely were my neighbours, and I had to manually delete them
through the CLI to be sure they'd actually gone.

3) VLC and probably other apps too have non standard ways to display files,
meaning these can pop up unexpectedly / leak data you perhaps don't want
shared.

4) I suspect this is probably a Samsung thing, but as my neighbour had been
using the Samsung Cloud service, there wasn't any way to disable this. It's
possible she just hadn't turned it off properly / was keeping it on for
device tracking. Either way, the device nagged me constantly to login to
Samsung Cloud and I'm absolutely not confident that it didn't do a stealthy
backup of all my datazzz. That's something to bear in mind, especially as
at one point the weather widget was clearly syncing with something external
and giving me entirely wrong info.

In the end I went through every app and checked them all individually, but
that's a lot more than I suspect most people would be interested in doing
;-)

Cheers

Cat

On Sat, 18 Nov 2023 at 15:56, Mick Fuzz <mickfuzz23 at gmail.com> wrote:

> Hi there,
>
> Has anyone got any tips / links to deleting data securely.
>
> Ideally using on linux / crossplatform tools? But open to others.
>
> There's one article here that is almost useful!
>
> https://www.wired.co.uk/article/securely-wipe-android-iphone-hard-disk
>
>
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>
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