Matthew Bryant @IAmMandatory of TheHackerBlog.com wrote a very detailed post on how he was able to register domains in .io that would essentially allow him to take over authoritative nameservers for the .io cctld.

It’s a very interesting post and shows many registries need to beef up their security protocols.

From the article:

Impact

Given the fact that we were able to take over four of the seven authoritative nameservers for the .io TLD we would be able to poison/redirect the DNS for all .io domain names registered. Not only that, but since we have control over a majority of the nameservers it’s actually more likely that clients will randomly select our hijacked nameservers over any of the legitimate nameservers even before employing tricks like long TTL responses, etc to further tilt the odds in our favor. Even assuming an immediate response to a large scale redirection of all .io domain names it would be some time before the cached records would fall out of the world’s DNS resolvers.

One mitigating factor that should be mentioned is that the .io TLD has DNSSEC enabled. This means that if your resolver supports it you should be defended from an attacker sending bad/forged DNS data in the way mentioned above. That being said, as mentioned in a previous post DNSSEC support is pretty abysmal and I rarely encounter any support for it unless I specifically set a resolver up that supports it myself.

Read the full article here