Re: [FD] SSH host key fingerprint - through HTTPS

From: Jeroen van der Ham <jeroen@dckd.nl>
To: Stephanie Daugherty <sdaugherty@gmail.com>
Cc: John Leo <johnleo@checkssh.com>,fulldisclosure@seclists.org,bugtraq@securityfocus.com
Subject: Re: [FD] SSH host key fingerprint - through HTTPS
Date:


Hi,

On 1 Sep 2014, at 10:43, Stephanie Daugherty <sdaugherty@gmail.com> wrote:

> Sure it shows me the fingerprint, but it doesn't tell me for sure if that's
> the RIGHT fingerprint or the fingerprint of an imposter,
> 
> It's entirely possible that both myself and that site are BOTH falling
> victim to a MITM attack.(routing attacks, DNS attacks, etc)
> 
> Proper host key verification (which nobody does) ideally means one or more
> of:
> * Verification that the SSH host key is connected via certificate chain to
> a trusted certificate,
> * Comparison to a fingerprint being posted on the organization's OWN https
> site
> * Comparison to a fingerprint provided with a GPG or S/MIME signature from
> the administrator of the machine.
> * Voice verification of the host public key or its fingerprint with the
> administrator of the machine.
> * Obtaining a printed copy of the host public key or its fingerprint
> directly from the administrator.
> 


There is a way now, using the \u201cmagic\u201d of DNSSEC and SSHFP records: http://tools.ietf.org/html/rfc4255

You use the DNSSEC hierarchy to create a trust chain. You can then securely publish a signed fingerprint of your SSH host key for that specific machine.

Jeroen.






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