Re: [Pana] Security Comment: draft-ohba-pana-relay-02.txt

[Margaret Wasserman <[e-mail]>]

Hi Alper,

On Nov 22, 2010, at 6:25 AM, Alper Yegin wrote:
> Hi Margaret,
>
> EAP and PANA protocols are designed to operate over unsecure links.
> They don't expect any encryption, integrity/replay protection, data  
> origin authentication from the layers below.
> As far as the EAP and PANA are concerned, PRE is no different than a  
> bridge or a router relaying the EAP/PANA payloads between the PaC  
> and the PAA.
>
I think there is an important difference between a Pana Relay (PRE)  
and a bridge or router relaying EAP/PANA packets.  In the router/ 
bridge case, the replies from the PAA are sent in an IP packet with a  
destination address of the Pana Client (PaC).  In order to snoop or  
intercept those packets, an attacker would need to be on-path between  
the PAA and the PaC.  When using PRE, the PAA responses are sent back  
to the PRE addresses which are not validated or authenticated in any  
way, so this would allow an easy way for an attacker to harvest a  
large number of replies for different PaCs without having to be on- 
path between the PAA and those PaCs.

That is a significant difference in the security model when a PRE is  
used.  Whether it is a difference that needs to be addressed in the  
protocol  depends on whether it would be problematic (within PANA/EAP,  
specifically) for a third-party to be able to harvest PAA replies for  
multiple clients.

The Security Considerations section needs to acknowledge this  
difference, and it (at least) needs to include some analysis of why  
this isn't a problem (if, in fact, it isn't).

Thanks,
Margaret