Re: Digital Ocean ssh key authentication security risk -- password authentication is re-enabled

[gp () gparent net]

Hello,

The last time I contacted them they did not care about this. It's 
basically a feature. They also used to (or still do) reset SSH host keys 
and other things.

A suggested workaround if I remember correctly was to set a sticky bit 
on the files you did not want their bootstrap script to modify. I have 
no idea if this works or if it makes sense as I worked around the 
problem another way.

Have you tried reaching support about it? I would expect you might get a 
different response depending on which tech you end up on.

-gp

On 2017-01-27 17:00, Daniel Elebash wrote:
> Regarding digitalocean.com cloud computing.
>
>
> PasswordAuthentication is reset to yes in  /etc/ssh/sshd_config when
> using ssh key authentication given the following scenario:
>
>
> When creating a new droplet from a snapshot where ssh key
> authentication "PasswordAuthentication" in /etc/ssh/sshd_config was
> previosly set to no, "PasswordAuthentication" is reset to yes.
>
>
> I am not sure how common this scenario is but for me I often create a
> base snapshot that is pre-configured with firewall settings, sudo
> user, ssh key authentication, various apps, hardening etc. that I can
> then use when spinning up a new server so I don't have to start from
> scratch.  By doing this  I was unaware that PasswordAuthentication was
> automatically re-enabled and that these servers were no longer secure
> via ssh key authentication only, leaving them open to Brute Force
> attacks.
>
>
> Steps to reproduce:
>
> Tested using an Ubuntu 16.04 droplet image
>
> 1. Create a  new Ubuntu 16.04 droplet and secure it using ssh key 
> authentication
> 2. Edit /etc/ssh/sshd_config and set PasswordAuthentication no
> 3. Reload ssh
> 4. Verify that you can log in using key authentication only, trying
> via password should be rejected.
> 5. Create a snapshot of this droplet
> 6. Create a new droplet from this snapshot
> 7. Open /etc/ssh/sshd_config and PasswordAuthentication will be reset 
> to yes
>
> You will now be able to log in via ssh using passwords instead of key
> authentication only.
>
>
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