Re: Re: Security advisory for musl libc - stack-based buffer overflow in ipv6 literal parsing [CVE-2015-1817]

[Rich Felker <dalias@libc.org>]

On Sat, Apr 18, 2015 at 05:49:51PM +0200, Harald Becker wrote:
> On 18.04.2015 17:25, Rich Felker wrote:
> >>The server hostkey will remain in process
> >>memory since it's required for rekeying - not as bad as root
> >>code execution though.
> >
> >Ugly. I don't see how this can be solved without a more advanced
> >privsep model. I agree it's lower-severity though.
> 
> IMO you may put the host keys in a file readable (not writable) with
> a dropbear group, and only using that group for dropbear (no other
> users or programs using that group). So you may read the keys even
> if not root, if you add this dropbear group to setgroups (not
> setgid) before dropping root privileges.

The key is already in memory. A design like the above would not
significantly improve security (except for heartbleed type issues); it
would be just like the situation now where the key is already in
memory. To make it more secure, the session process would not have any
access to the key and would have to communicate with an existing
privileged process to rekey.

Rich