Re: [TLS] draft-rescorla-tls-renegotiate and MITM resistance
Yoav Nir <ynir@checkpoint.com> Mon, 09 November 2009 21:05 UTC
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From: Yoav Nir <ynir@checkpoint.com>
To: David-Sarah Hopwood <david-sarah@jacaranda.org>, "tls@ietf.org" <tls@ietf.org>
Date: Mon, 09 Nov 2009 23:05:59 +0200
Thread-Topic: [TLS] draft-rescorla-tls-renegotiate and MITM resistance
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Subject: Re: [TLS] draft-rescorla-tls-renegotiate and MITM resistance
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David-Sarah Hopwood wrote: > Marsh Ray wrote: >> Yair Elharrar wrote: >>> In addition, until such time that all clients in the world start >>> supporting this extension (e.g. kiosks in airports), servers will >>> have to support backward compatibility. >> >> It will be a trade-off for each server admin to weigh and decide their >> policy. I suspect many admins will prefer not to allow insecure >> connections from unpatched airport kiosks. > > To prevent this attack, they don't have to disallow connections, only > renegotiations in which the extension is not used. Even that can be further refined. You can freely renegotiate an authenticated session, as long as the renegotiation does not involve an identity change. Obviously, if the first handshake include client authentication, any renegotiation that includes the same client cert is fine. If the session is authenticated by the application (as in an HTTPS login page) it's also possible to renegotiate with impunity, but the interaction here between the application and the TLS layer may be too sensitive an bug prone to specify in the draft. For example, if an SSTP server renegotiates after the client has authenticated (through PPP), I don't think there's a security risk in not implementing the extension.
- [TLS] draft-rescorla-tls-renegotiate and MITM res… Yair Elharrar
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Yoav Nir
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Marsh Ray
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Yoav Nir
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Dr Stephen Henson
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Yair Elharrar
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Yoav Nir
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Nicolas Williams
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… David-Sarah Hopwood
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… David-Sarah Hopwood
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Yair Elharrar
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Yngve N. Pettersen (Developer Opera Software ASA)
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Marsh Ray
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Yoav Nir
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Marsh Ray
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Nicolas Williams
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Marsh Ray
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… David-Sarah Hopwood
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Michael D'Errico
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Nicolas Williams
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Marsh Ray
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Nicolas Williams
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Steve Dispensa
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… David-Sarah Hopwood
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Peter Saint-Andre
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Marsh Ray
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Yoav Nir
- Re: [TLS] To API or not Bill Frantz
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Martin Rex
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Michael D'Errico
- Re: [TLS] draft-rescorla-tls-renegotiate and MITM… Martin Rex
- [TLS] RC4+3DES rekeying - long-lived TLS connecti… Martin Rex
- Re: [TLS] RC4+3DES rekeying - long-lived TLS conn… David-Sarah Hopwood
- Re: [TLS] RC4+3DES rekeying - long-lived TLS conn… Peter Saint-Andre