USSD Traffic analysis

ty tyruskam at gmail.com
Tue Feb 7 12:18:46 UTC 2012


Thanks for your insight Harald.

I work for one of the leading mcommerce providers in the country as a
security analyst and from the architectures, yes all the transactions take
place via secure channels. However, my concern has always been after the
transaction leaves the application and is handed over to the USSD gateway
for the MNO, is it possible at an SS7 layer to intercept the said traffic?

I haven't seen any research into how USSD can be intercepted OTA just like
GSM voice calls have been intercepted.

Your thoughts are highly appreciated

-ty

On Tue, Feb 7, 2012 at 3:11 PM, Harald Welte <laforge at gnumonks.org> wrote:

> Hi!
>
> On Tue, Feb 07, 2012 at 01:05:04PM +0300, ty wrote:
> > specifically Kenya, there is a proliferation of financial services over
> > USSD and this begs the question just how secure is it? If anyone on the
> > list might have done a bit of digging around I'd really love to share
> > learnings and insights.
>
> Typically those mobile payment applications are SIM application toolkit
> based and the SIM card uses encrypted SMS to talk to the back-end
> server.  So assuming that the crypto was done properly, there's nothing
> wrong with such an architecture.
>
> There are some services that use USSD, but then you can only transfer
> between accounts that you have previously authorized to be used this way
> using a more secure transport channel.  Typically people list only their
> own account to transfer between prepaid and bank account this way, so
> the fraud potential seems limited.
>
> Regards,
>        Harald
> --
> - Harald Welte <laforge at gnumonks.org>
> http://laforge.gnumonks.org/
>
> ============================================================================
> "Privacy in residential applications is a desirable marketing option."
>                                                  (ETSI EN 300 175-7 Ch. A6)
>
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