mobile phone + password = 2 factor auth?

[Seth Vidal]

On Tue, 26 May 2009, Till Maas wrote:

> On Tuesday 26 May 2009 15:50:49 Seth Vidal wrote:
>> I was changing some settings with my mobile phone company and in order to
>> change my password they made me use what looks a lot like 2 factor auth:
>>
>> something I know: my current password
>> something I have: my phone
>>
>> I logged in with my current password - then they txt'd me a temporary
>> password which I had to type in to verify I was me.
>>
>> Which got me to wondering - if most people have a mobile phone and/or have
>> access to one - why couldn't we use that as the second factor for our
>> auth?
>
> 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.
>

But that's the point of it being one factor of two factor auth...

Even if you compromise the txt msg you still don't have the component 
that the user knows. You only have the component that the user HAS.

-sv