[TLS] Definition of "lenient server"
David-Sarah Hopwood <david-sarah@jacaranda.org> Fri, 20 November 2009 05:54 UTC
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Sender: David-Sarah Hopwood <djhopwood@googlemail.com>
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Date: Fri, 20 Nov 2009 05:53:00 +0000
From: David-Sarah Hopwood <david-sarah@jacaranda.org>
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Subject: [TLS] Definition of "lenient server"
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David-Sarah Hopwood wrote: > 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). Gack, sorry, typo. A lenient server is a server that does accept *renegotiating* handshakes with an unpatched client (which obviously makes it vulnerable in that case). Both lenient and strict servers accept initial handshakes from any client. I don't think there is ever a reason to reject initial handshakes where no client certificate is used. There might be a reason to reject initial handshakes where a client cert is used, in order to prevent the variant of an attack where the client sees the renegotiation, and is unpatched. > However, a lenient > server, unlike an unpatched server, will detect an attack on connections > with a patched client. That is, on any connection 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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- Re: [TLS] simplistic renego protection Joseph Salowey (jsalowey)
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Eric Rescorla
- Re: [TLS] simplistic renego protection Eric Rescorla
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Eric Rescorla
- Re: [TLS] simplistic renego protection Eric Rescorla
- Re: [TLS] simplistic renego protection Marsh Ray
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Blumenthal, Uri - 0662 - MITLL
- Re: [TLS] simplistic renego protection Michael D'Errico
- Re: [TLS] simplistic renego protection Marsh Ray
- Re: [TLS] simplistic renego protection Michael D'Errico
- Re: [TLS] simplistic renego protection Marsh Ray
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Nelson B Bolyard
- Re: [TLS] simplistic renego protection Michael D'Errico
- Re: [TLS] simplistic renego protection Michael D'Errico
- Re: [TLS] simplistic renego protection peter.robinson
- Re: [TLS] simplistic renego protection Yngve N. Pettersen (Developer Opera Software ASA)
- Re: [TLS] simplistic renego protection Stephen Farrell
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Michael D'Errico
- Re: [TLS] simplistic renego protection Eric Rescorla
- Re: [TLS] simplistic renego protection Nasko Oskov
- Re: [TLS] simplistic renego protection Blumenthal, Uri - 0662 - MITLL
- Re: [TLS] simplistic renego protection Michael D'Errico
- Re: [TLS] simplistic renego protection Yair Elharrar
- Re: [TLS] simplistic renego protection Steve Dispensa
- Re: [TLS] simplistic renego protection Eric Rescorla
- Re: [TLS] simplistic renego protection Eric Rescorla
- Re: [TLS] simplistic renego protection Marsh Ray
- Re: [TLS] simplistic renego protection Michael D'Errico
- Re: [TLS] simplistic renego protection Eric Rescorla
- Re: [TLS] simplistic renego protection Robert Dugal
- Re: [TLS] simplistic renego protection Pasi.Eronen
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Simon Josefsson
- Re: [TLS] simplistic renego protection Stefan Santesson
- Re: [TLS] simplistic renego protection Stefan Santesson
- Re: [TLS] simplistic renego protection Eric Rescorla
- Re: [TLS] simplistic renego protection Eric Rescorla
- Re: [TLS] simplistic renego protection Michael D'Errico
- Re: [TLS] simplistic renego protection Michael D'Errico
- Re: [TLS] simplistic renego protection Michael D'Errico
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Marsh Ray
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection Marsh Ray
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection Nasko Oskov
- Re: [TLS] simplistic renego protection Nelson B Bolyard
- Re: [TLS] simplistic renego protection Nelson B Bolyard
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Michael D'Errico
- Re: [TLS] simplistic renego protection Nelson B Bolyard
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- [TLS] Definition of "lenient server" David-Sarah Hopwood
- Re: [TLS] simplistic renego protection Stefan Santesson
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection Stefan Santesson
- Re: [TLS] simplistic renego protection Ben Laurie
- Re: [TLS] simplistic renego protection Stefan Santesson
- Re: [TLS] simplistic renego protection Bill Frantz
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection Stefan Santesson
- Re: [TLS] simplistic renego protection Marsh Ray
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection Ben Laurie
- Re: [TLS] simplistic renego protection David-Sarah Hopwood
- Re: [TLS] simplistic renego protection Ben Laurie
- Re: [TLS] simplistic renego protection Pasi.Eronen
- Re: [TLS] simplistic renego protection Martin Rex
- Re: [TLS] simplistic renego protection Pasi.Eronen
- Re: [TLS] simplistic renego protection Yngve Nysaeter Pettersen
- Re: [TLS] simplistic renego protection Peter Gutmann
- Re: [TLS] simplistic renego protection Kyle Hamilton