On Thu, 2018-05-10 at 01:38 +0000, Ryan Taylor wrote: > > If this is correct, using the servercert option is a significant security problem. > > Perhaps the servercert option is not intended to be used for any sort of security guarantee > whatsoever. However if that is the case, there should probably be a warning in the man page, and > also printed on standard output, kind of like overriding a web browser to connect to a site with an > untrusted certificate. Users who have not done the math or read the man page carefully may be using > this option with the mistaken belief that it provides some security assurance via a sort of > makeshift certificate pinning. > > Or, this could be fixed by requiring a complete match of the hash instead of just 4 characters. > What are the "certain testing use-cases" and how important are they compared to the security > considerations? Hi Ryan, thanks for looking at this. As Dan says, if a user provides a truncated hash then we do require the match to be at the beginning of the hash. It's not just *any* substring. Even so, yes: 4 characters isn't many, so there's a fair chance of a false match. Ultimately, Don't Do That Then. I'm happy to improve the documentation to make it clear that there is absolutely no excuse for a user to use anything less than the full hash in "production" use, or indeed in any circumstance where cut-and-paste works. I vaguely recall that I had similar reservations when this feature was first added (Nikos, was it you?). But I *have* found it useful occasionally in testing, in strange setups where I haven't been able to cut and paste for some reason. At the time, we were forcibly removing the "--no-cert-check" option because I threw my toys out of the pram after finding people advocating its use in production ? so even a 4- char match was better than that! :) -------------- next part -------------- A non-text attachment was scrubbed... Name: smime.p7s Type: application/x-pkcs7-signature Size: 5213 bytes Desc: not available URL: <http://lists.infradead.org/pipermail/openconnect-devel/attachments/20180510/43db1f3e/attachment.bin>
