Issue 27: Security and path testing (was: Comments on draft-ietf-mobike-protocol-00.txt)

[email protected] writes:
> - An attacker could modify the contents of the messages. 
> 
>   Modifying the COOKIE2 payload has the same effect as dropping 
>   the message (initiator thinks the path does not work, reasonably
>   correctly so), so no benefit from integrity protection here
>   either.

Nope. The section 2.6 says that if N(COOKIE2) values do not match the
IKE_SA MUST be closed... so modifying the path test message COOKIE2,
allows easy DoS attack with single modified packet to close the whole
connection, and as the path test message only has constant data
otherwise, it will cause attacker to be able to create those packets
by just knowing IP and port numbers of the connection...

Or is the COOKIE2 processing different in the informational exchange
and in the path test exchange? If so that is not mentioned in the
draft anywhere. 

> And encrypting and integrity protecting these messages is not as
> easy as it sounds. For instance, if the response message is

It is actually quite easy, we simply do not use separate exchange for
those...

Not using separate exchange (i.e. getting rid of PATH_TEST exchange)
means that we simply need to define the proper retransmission policy
for IKE packets (which we need to do anyways, and which is missing
from the document), and we need to say that NO changes to the
IKE_SA IP-addresses are done ever unless the there explicit request by
CHANGE_PATH nofity from the other end.

(I will write more about that along with my comments of the draft). 
-- 
[email protected]