On Tue, May 26, 2009 at 10:08 AM, Till Maas <opensource(a)till.name> wrote:
On Di Mai 26 2009, Seth Vidal wrote:
> On Tue, 26 May 2009, Till Maas wrote:
> > On Di Mai 26 2009, Jesse Keating wrote:
> >> On Tue, 2009-05-26 at 17:44 +0200, Till Maas wrote:
> >>> A problem with phones is, that they are typically not as secure as
> >>> hardware tokens. Users can install custom software on them. Also the
> >>> phone may be compromised via bluetooth. It might be even possible to
> >>> directly access text messages via bluetooth or maybe also wifi
> >>> nowadays.
> >> Wouldn't that be why you have to combine what comes up on your phone
> >> with the password you know, so that just the phone alone can't get you
> >> in?
> > Here is another attack scenario: The attacker first attacks the desktop
> > to obtain the password. But then he also compromises the phone once it is
> > connected to the desktop to synchronize some data, e.g. contacts, music
> > or software. Then the attacker got both factors without having physical
> > access on the phone.
> Both of them assume an attacker targetting someone on our system.
Why is this? Even an attacker that got access to your desktop without
specifically targetting a Fedora infrastructure team member can afterwards
compromise your phone, once he noticed that you use it to login to Fedora. The
browser cache or e-mails may indicate that you login to Fedora and some config
files for phone synchronization can show the attacker, how the phone can be
Part of security work is analysis of the perceived risk and mitigation
strategies or acceptance of that risk.
I think that using a mobile phone as part of a two-factor auth scheme
is a good idea, despite the inherent risks of the platform. It's a
relatively low cost item that nearly everyone has or can obtain.
While it's not a very secure object on it's own, I think that because
it's only one factor in a two factor scheme, it's still useful and
'good enough' for this purpose. I would be willing to accept the risks
of using this as a part of our auth scheme. My perception of those
risks is that there is a sufficient level of effort required on the
part of the attacker as to make an attack non-trivial and reasonably