DNS in applications a rebuttal

There’s an awful lot going on in the world of DoH at the moment – so rather than writing one huge rambling post I’m going to try and cover everything in several shorter rambling posts. I’m going to start with taking a look at a presentation that Mozilla did regarding “DNS in applications”, which I have many issues with and I think highlights the fundamental disconnect between the Mozilla developers and people that actually have to deal with network and user security. A lot of this has been discussed extensively on the IETF “Applications doing DNS” discussion list. If you’re on that list I’m not going to be saying anything much new, but with that said let’s start looking at the presentation. Continue reading

Defence against the DoH! Arts

I’m afraid it’s another post about DNS-over-HTTPS, but there’s a lot going on. Whilst the current crop of DoH servers don’t suffer from the same problems as normal open DNS resolvers, they do have issues of their own. Whilst fans of DoH are right when they that nothing stopped applications from doing their own DNS before and that the bad guys have always tunnelled data over other protocols. It is also true that DoH has massively lowered the bar for them both in terms of readily available libraries and in the provision of vast, highly resilient, free, tunnelling infrastructure provisioned by reputable companies. However I don’t want to get back into that again, instead lets review the latest happenings in the world of Doh. In the last month we’ve had : a DoH controlled spam campaign, the first malware to leverage DoH and Mozilla nominated for Internet villain of the… Continue reading

DoH no!

As was entirely predictable DNS-over-HTTPS has now been implicated in a spam campaign. Google DoH instance was used to access TXT records to control the spam campaign via a bit of javascript on web pages. This isn’t a weakness in DNS or for that matter in DoH, it’s just using Googles DoH as a side channel. They could have achieved the same thing by accessing a specific web page, but that would be more easily blocked or shut down. There are also mobile application, both IOS and android, that are using DoH by default without giving the user a choice in the matter*. At this point if you use DNS as part of your security posture – either via RPZ, pi-hole or some other mechanism ( and if you aren’t you really should ) then you need to be blocking DoH. At present there are over 70 advertised public DoH… Continue reading

The state of DNS security records 2019

Record type occurence

My recent search for DNS hosting, reminded me that it’s been a while since my first state of DNS report. I had meant to do it every year so this is a bit late, I should probably set myself a reminder. At this point lets just say I missed 2018 and this is the 2019 report and I’ll try to remember for 2020. TLDR: Summary The deployment of security records in DNS has got slightly worse. The average score (out of 10) based on deployment of CAA, DKIM, DMARC, DNSSEC and SPF was 2.48 in 2017 , the same records checked today averaged 2.15 with this years data set averaging 2.42. Two data sets where used this year, the 2017 lists and updated lists taken from the same sources. Usage of IPv6, SPF and DMARC have seen significant decreases across both sets of data, off set only slightly by the… Continue reading