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Up to 20 million people could get broken internet in domain security rollover

Kevin Murphy, November 9, 2017, 14:42:00 (UTC), Domain Tech

Twenty million people losing access to parts of the internet is considered an acceptable level of collateral damage for ICANN’s forthcoming DNS root security update.

That’s one of a number of facts and figures to emerge from recent updates from the organization, explaining its decision to delay the so-called “KSK rollover” from October 11 to some time in the first quarter next year.

The rollover will see a new Key Signing Key, used as the trust anchor for all DNSSEC-signed domains, replace the seven-year-old original.

DNSSEC protects internet users and registrants from domain-based man-in-the-middle attacks. It’s considered good practice to roll keys at each level of the DNS hierarchy periodically, to reduce the risk of successful brute-force attacks.

The root KSK update will affect hundreds of millions of people who currently use DNSSEC-compatible resolvers, such as Google DNS.

ICANN delayed the rollover after it, rather fortuitously, spotted that not all of these resolvers are configured to correctly handle the change.

The number of known incompatible servers is quite small — only about 500 of the 11,982 DNSSEC-using recursive servers initially surveyed (pdf). That represents only a very small minority of the world’s internet users, as most are not currently using DNSSEC.

Subsequent ICANN research, presented by principal researcher Roy Arends at ICANN 60 last week, showed that:

  • There are currently about 4.2 million DNS resolvers in the world.
  • Of those, 27,084 are configured to tell the root servers which KSKs they support (currently either the KSK-2011 or KSK-2017).
  • Of those, 1,631 or 6.02% do not support KSK-2017

It was only possible to survey servers that have turned on a recent update to DNS software such as BIND and Unbound, so the true number of misconfigured servers could be much higher.

Matt Larson, ICANN’s VP of research, told DI that ICANN has identified 176 organizations in 41 countries that are currently not prepared to handle the new KSK. These organizations are fairly evenly spread geographically, he said.

Since making the decision to delay the rollover, ICANN has hired a contractor to reach out to these network operators to alert them to potential problems.

ICANN’s CEO Goran Marby has also been writing to telecommunications regulators in all countries to ask for assistance.

After the rollover, people using an incompatible resolver would be unable to access DNSSEC-signed domains. Again, that’s still quite a small minority of domains — there are only about 750,000 in .com by some accounts and apparently none of the top 25 site support it.

ICANN could roll back the change if it detects that a sufficiently large number of people are negatively affected, but that number turns out to be around 20 million.

According to its published rollover plan:

Rollback of any step in the key roll process should be initiated if the measurement program indicated that a minimum of 0.5% of the estimated Internet end-user population has been negatively impacted by the change 72 hours after each change has been deployed into the root zone.

According to InternetWorldStats, there were around 3,885,567,619 internet users in the world this June. It’s very likely more people now.

So a 0.5% threshold works out to about 19 million to 20 million people worldwide.

Larson agreed that in absolute terms, it’s a big number.

“The overall message to take away from that number, I suggest, is that a problem would have to be pretty serious for us to consider rolling back,” Larson, who was not on the team that came up with the threshold, said.

“I think that’s a reasonable position considering that, in the immediate aftermath of the rollover, there are two near-immediate fixes available to any operator experiencing problems: update their systems’ trust anchors with the new key or (less desirable from my perspective but still effective) simply disable DNSSEC validation,” he said.

He added that the 0.5% level is not a hard and fast rule, and that ICANN could be flexible in the moment.

“For example, if when we roll the key, we find out there’s some critical system with a literal life or death impact that is negatively affected by the KSK roll, I think I can pretty confidently state that we wouldn’t require the 0.5% of Internet user threshold to be met before rolling back if it looked like there would be a significant health and safety risk not easily mitigated,” he said.

The chances of such an impact are very slim, but not impossible, he suggested.

It’s not ICANN’s intention to put anyone’s internet access at risk, of course, which is why there’s a delay.

ICANN’s plan calls for any rollover to happen on the eleventh day of a given calendar quarter, so the soonest it could happen would be January 11.

Given the complexity of the outreach task in hand, the relative lack of data, and the holiday periods approaching in many countries, and ICANN’s generally cautious nature, I’d hazard a guess we might be looking at April 11 at the earliest instead.

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