During the development of the DNS Knot Resolver, CZ.NIC Labs have managed to reveal a security flaw that makes it possible to bypass DNSSEC security on F5 load balancers and cause denial of service. These products are being used, for example, in some internet banking applications, including those of Czech banks and public authorities. From the perspective of a user attempting to access an internet banking service, a successful attack exploiting this error would manifest in the browser suddenly reporting an “address not found” error and the service becoming unavailable.
A global DNS maintenance is scheduled for February 1, 2019, and authoritative server operators must get ready for it. That is why we dedicate our today’s article to the state of readiness of .CZ domains for changes that will be effective from the beginning of next month.
DNS has been in use on the Internet for more than 30 years — now it is time for its worldwide maintenance that shall, for the first time in the existence of DNS, require coordinated actions from all operators of DNS servers and DNSSEC validators.
Over past years, various DNS software developers tried to solve the problems with the interoperability of the DNS protocol and especially its EDNS extension (RFC 6891 standard), by temporary workarounds, which aimed to lend their software an ability to temporarily accept various non-standard behaviors. Unfortunately, time has shown that this attitude of adding temporary workarounds is not a long-term solution, especially because the implementations not fully complying with standards were seemingly functional and there was no reason for a permanent fix. The result of these makeshift solutions is their accumulation in the DNS software, leading to a situation where there are so many of them that they themselves begin to cause problems. The most obvious problem is slower response to DNS queries and the impossibility to deploy new DNS protocol feature called DNS Cookies, which would help reduce DDoS attacks based on DNS protocol abuse.
On July 16-21, 2017, the IETF 99 conference will take place in Prague. What IETF is and how it works has been already explained by my colleague Ondřej Surý in Czech Cesta do hlubin IETF, Odkud pochází internetové standardy (aneb bylo jednou jedno RFC) or Vrána k vráně sedá aneb koťátka, dogy a nápoje v IETF. Ladislav Lhotka, in turn, described its unusual geeky atmosphere IETF: internet podle mručící většiny. So it is enough to mention that IETF is an organization that publishes Internet standards. Its goal is to create quality technical documentation that influences the development of the Internet and its applications.