Wouldn't simply including a hub challenge style verification for sent
updates address this?  Redirecting DNS to a targeted URL, like
http://google.com/, is likely to return an HTTP status code of 2xx
simply because it won't specifically be looking for PSHB updates.  But
it's very unlikely to look for and return a valid hub challenge string
when receiving that update.  Once that fails a few times the
subscription would get dropped.

That's far from perfect, but it's a step better than allowing hubs to
be a blind relay.


On Sun, Nov 22, 2009 at 12:41 AM, Pádraic Brady <[email protected]> wrote:
> Subscribers track their subs too so it's simple to refuse non-matching 
> updates quickly with a 404. But that's playing softball - the entire attack 
> relies on the Subscriber's server being misconfigured or vulnerable to start 
> with. So this is largely FUD - the same risk applies to all pubsub models 
> relying on DNS. The protocol can't address unrelated security issues.



-- 
Joseph Scott
[email protected]
http://josephscott.org/

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