[Security] S2S Leap of faith w/ SASL EXTERNAL
dave at cridland.net
Thu Nov 18 16:57:12 CST 2010
On Thu Nov 18 00:51:26 2010, Kim Alvefur wrote:
> Imagine a server with a self signed certificate. When your server
> connects to it, it of course would't trust the cert enough to do
> EXTERNAL, so it falls back to dialback. If dialback is successfully
> a few times, while the server presents the same cert, automatically
> it and allow SASL EXTERNAL the next time.
Actually, just doing leap-of-faith the first time is sufficient.
You're allowing full dialback as authentication anyway, so in
practise, this isn't losing you any security, whereas by having to
build trust in a server, you're providing a larger window for an
attacker to disrupt.
It's also, of course, not gaining any security - it is gaining
optimization, but at the risk that an attacker can disrupt, and
takeover, a server if he times it *just* so. (Or, if your LoF
certificate store isn't persistent and he figures out how to crash
Dave Cridland - mailto:dave at cridland.net - xmpp:dwd at dave.cridland.net
Infotrope Polymer - ACAP, IMAP, ESMTP, and Lemonade
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