[Openid-specs-fapi] [Bitbucket] Issue #127: CIBA: security issues (openid/fapi)

Dave Tonge dave.tonge at momentumft.co.uk
Tue Nov 28 22:02:48 UTC 2017

Tom, there seems to be some confusion here. The CIBA profile provides a
standard for backchannel auth. It is not tied to mobile phones even, it is
just that the first "use case" was for Mobile Connect.

In FAPI we are proposing that banks use CIBA in the following way:

   1. A bank onboards a customer to the bank's mobile app (this is in the
   competitive space, but this onboarding process should hopefully include the
   generation of a key-pair, with a private key that never leaves that device).
   2. The customer uses this banking app for everyday banking interactions
   - the bank can obviously implement this in any way they see fit
   3. The bank implements CIBA and defines some login_hint that third
   parties can use to start a CIBA request - this could be a username, an
   email address, a card number, etc.
   4. When the bank receives a CIBA request from a valid client with a
   valid login_hint, it sends a push notification to the user's device. (NB,
   not an SMS, but rather an Apple or Android push notification)
   5. The user opens their banking app from the push notification and is
   shown a consent screen where they can authorize the requested access
   6. Once the user authorizes the request, the client is issued an access

(NB the flow will probably include the comparison of binding messages, but
we are still working through the detail of that)

The bank should have as strong an assurance that it is interacting with its
user as any other time that the user is using the banking app.

An attacker couldn't spoof this flow by hijacking the user's phone number
as the flow doesn't use SMS messages or any telco based identity factors.

If an attacker hijacked the Apple / Google push notification system, the
flow still wouldn't break as the banking app would need to retrieve the
consent details to display directly from the the bank's servers.

Hopefully, this clarifies the proposed use case of CIBA in a FAPI context.


On 28 November 2017 at 16:12, Tom Jones via Openid-specs-fapi <
openid-specs-fapi at lists.openid.net> wrote:

> To be really clear then. Only the telco can support CIBA, correct?
> Note that i voted against the MODRNA specs because, IMO, they do not
> uphold the user consent requirements in OpenID Connect. For FAPI to endorse
> the telco involvement in a financial transaction would exacerbate this
> failing.
> ..tom
> Peace ..tom
> On Tue, Nov 28, 2017 at 7:16 AM, Gonzalo Fernández <
> issues-reply at bitbucket.org> wrote:
>> [image: xixon2002]
>> *Gonzalo Fernández* commented on issue #127:
>> CIBA: security issues
>> <https://bitbucket.org/openid/fapi/issues/127/ciba-security-issues>
>> Hi Nat,
>> Telcos companies do know the device associated with a user, in fact they
>> use such information to improve customer care when he calls for something
>> related with the device. As far as I know, when the terminal has been
>> registered in the network, it sends the IMEI and thanks to that the
>> operator is able to know the device and associated it to the MSISDN and
>> IMSI because at this time it also has that information.
>> View this issue
>> <https://bitbucket.org/openid/fapi/issues/127/ciba-security-issues> or
>> add a comment by replying to this email.
>> Unsubscribe from issue emails
>> <https://bitbucket.org/api/1.0/repositories/openid/fapi/issue/127/unsubscribe/tomcjones/f30a0030618b6476696b7a6f4abe3a0090d0f6ad/>
>> for this repository. [image: Bitbucket] <https://bitbucket.org>
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Dave Tonge
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