bug#44808: Default to allowing password authentication on leaves users vulnerable

[raingloom <raingloom@riseup.net>]

On Mon, 23 Nov 2020 03:32:08 +0100
Taylan Kammer <taylan.kammer@gmail.com> wrote:

> On 23.11.2020 00:20, Christopher Lemmer Webber wrote:
> > Okay, I just realized I left a friend vulnerable by guiding them
> > through a Guix graphical install and telling them it would give
> > them a decent setup.  They turned on openssh support.
> > 
> > Then I realized their config had password-authentication? on.
> > 
> > That's unacceptable.  We need to change this default.  This is
> > known to leave users open to attack, and selecting a password
> > secure enough against brute forcing is fairly difficult, much more
> > difficult than only allowing entry by keys.  Plus, few
> > distributions do what we're doing anymore, precisely because of
> > wanting to be secure by default.
> > 
> > Yes, I know some people want password authentication on as part of a
> > bootstrapping process.  Fine... those users know to put it on.
> > Let's not leave our users open to attack by default though.
> > 
> > Happy to produce a patch and change the documentation, but I'd like
> > to hear that we have consensus to make this change.  But we should,
> > because otherwise else I think we're going to hurt users.  
> 
> I think most ideal would be if the user is asked the following two 
> questions, with a short explanation of what each means:
> 
> - Allow root login via SSH?
> 
> - Allow password authentication in SSH?
> 
> (I think Debian does this.)
> 
> Because as you say, on one hand password authentication in SSH can be
> a security risk.  But on the other hand many machines never have
> their SSH port exposed to the Internet, and the intranet is assumed
> to be safe. In those cases it would be an annoyance to have to enable
> it manually.
> 
> Both points apply to direct root login as well I think.
> 
> Allowing password authentication but disabling root login might also
> be considered safe enough on machines exposed to the Internet,
> because the attacker needs to guess the username as well.  Only
> presents a small increase in complexity for the attacker though.
> 
> 
> - Taylan
> 
> 
> 

Most people won't know why allowing password authentication is
unsecure. Either it should be worded differently, have a warning, or
not be an option.

Same goes doubly so for allowing root login.