Re: [TLS] simplistic renego protection

[David-Sarah Hopwood <david-sarah at jacaranda.org>]

Nelson B Bolyard wrote:
> On 2009-11-19 11:20 PST, David-Sarah Hopwood wrote:
>> David-Sarah Hopwood wrote:
>>> Nasko Oskov wrote:
> 
>>>> If the MiTM sends a client hello to the server that has no extension,
>>>> then the server has no way to drop the connection. This will require
>>>> a strict server to prevent the attack and strict server config will
>>>> not be reality for a long time. What am I missing?
>>>
>>> That, in the RI approach, strict server config is essential from the
>>> start.
>>
>> Point of clarification: "strict server" here means that the server does 
>> not accept *renegotiations* with an unpatched client. It still accepts 
>> initial handshakes.
> 
> If that is a "strict server", then what is a "lenient server"?
> Is it a vulnerable server?

A server that does accept initial handshakes with an unpatched client
(which obviously makes it vulnerable in that case). However, a lenient
server, unlike an unpatched server, will detect an attack on connections
with a patched client.

I believe this is not enough to consider the server to have been "fixed",
and I think it's a bad idea to end up with a subset of servers that
appear to be patched, but are still vulnerable on some connections.

-- 
David-Sarah Hopwood  ⚥  http://davidsarah.livejournal.com

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