Re: CVE-request: systemd-resolved DNS cache poisoning

[Florian Weimer <fweimer () redhat com>]

On 11/12/2014 12:15 PM, Sebastian Krahmer wrote:
> At its simplest, an attacker triggers a query to a domain he controls
> via SMTP or SSH-login. Upon receipt of the question, he can just add
> any answer he wants to have cached to the legit answer he provides
> for the query, e.g. providing two anser RR's: One for the question asked
> and one for a question that has never been asked - even if the DNS server
> is not authoritative for this domain.

BIND 9 is supposed to filter such garbage from upstream answers, but 
there are other resolvers out there which will pass through such answers 
unchanged, so this is very much CVE-worthy.

(This systemd component is optional, I strongly recommend not to ship 
it.  It's not even possible right now to dump the cache contents to 
debug such issues.)

--
Florian Weimer / Red Hat Product Security