[Pdns-users] PowerDNS Security Announcement 2016-01

Alejandro Adroher Mellado alejandro.adroher at omniaccess.com
Fri Sep 9 14:02:08 UTC 2016

Thanks Remi.

-----Original Message-----
From: Pdns-users [mailto:pdns-users-bounces at mailman.powerdns.com] On Behalf Of Remi Gacogne
Sent: viernes, 9 de septiembre de 2016 15:45
To: pdns-users at mailman.powerdns.com
Subject: Re: [Pdns-users] PowerDNS Security Announcement 2016-01

Hi Alejandro,

On 09/09/2016 03:27 PM, Alejandro Adroher Mellado wrote:
> I have 5 of the affected Authoritatives with version 3.4.7. Before to 
> update the version up to 3.4.10 or 4, I'd like to protect them with 
> dnsdist, but the QNameWireLengthRule and QNameLabelsCountRule has been 
> added on last dnsdist version 1.1.0-beta1, and we have  1.0.0.
> There is any way to be protected using dnsdist v 1.0.0 ... at least 
> during the weekend before the proper updates I will on next week?

First of all, keep in mind that the issues fixed in 3.4.10 are of low to medium severity only, and simply having dnsdist in front of your servers already mitigates CVE-2016-5426 since dnsdist will drop qnames with a wirelength > 255.

Ideally I would advise upgrading to dnsdist 1.1.0-beta1 if you can, because filtering would be much easier then. That being said in dnsdist
1.0.0 you can use addLuaAction() and a bit of Lua code to do some basic checks. dq.qname:toString() will give you a string representation of the query's qname.

Remi Gacogne
PowerDNS.COM BV - https://www.powerdns.com/

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