DNS Filtering Legislation Would Derail DNSSEC, Experts Contend

A key provision in an intellectual property protection bill that was approved today by the Senate Judiciary Committee could sabotage Internet security and, specifically, DNSSEC, according to a who's who of Internet infrastructure and security experts, including Dan Kaminsky.

The PROTECT (Preventing Real Online Threats to Economic Creativity and Theft of Intellectual Property Act) IP Act calls for using recursive DNS servers to blacklist and block domain names of servers offering pirated music or other illegally obtained intellectual property. A group of renowned Internet security experts including Kaminsky released a white paper explaining how forcing these millions of recursive servers on the Internet to filter out DNS requests to those sites would basically cripple the emerging DNSSEC technology. DNSSEC is currently in the process of being adopted on the Internet; it provides verification that the site a user visits is indeed that site and not a spoofed or redirected one.

Along with Kaminsky, who discovered and helped get patched a serious flaw in DNS, the authors of the paper include Steve Crocker, an IETF pioneer and CEO of Shinkuro; David Dagon, a post-doctoral researcher at Georgia Institute of Technology studying DNS security and a co-founder of Damballa; Danny McPherson, chief security officer for VeriSign; and Paul Vixie, principal author of the pervasive BIND DNS server software and creator of several DNS standards.

The authors say they support enforcement of intellectual property rights, but that the DNS filtering requirement would stymie federal government and private industry efforts for beefing up Internet security -- namely DNSSEC. And the filters could easily be bypassed and therefore be unlikely to quell online copyright infringement, they say.

"It's like trying to make a telephone that won't carry swear words," Kaminsky says of the DNS-filtering approach.

They maintain that the DNS filtering -- which would force the censoring of websites via blacklists published by the Department of Justice -- would clash with DNSSEC by encouraging the brand of network manipulation that DNSSEC aims to prevent.

"The only possible DNSSEC-compliant response to a query for a domain that has been ordered to be filtered is for the lookup to fail," the paper says. That would make a hacked name-server and a filtered one "indistinguishable," it says. "Moreover, any filtering by nameservers, even without redirection, will pose security challenges, as there will be no mechanism to distinguish court-ordered lookup failure from temporary system failure, or even from failure caused by attackers or hostile networks."

David Ulevitch, CEO and founder of OpenDNS, which runs a recursive DNS service, says the bill is a bad idea. It could encourage the use of non-U.S. DNS servers, which would be out of the jurisdiction of the U.S. law. "The bad guys are resourceful," he says. And for DNS service providers such as OpenDNS and major ISPs, it would be tricky to implement the DNS blacklists they would be given by the U.S. Department of Justice: "Technically, it's extremely challenging to enforce that. [The lawmakers] have underestimated the technical implications, which seem overly arduous," Ulevitch says.

PROTECT IP is a tweaked and renamed version of what was formerly the Combating Online Infringements and Counterfeits Act (COICA), which was put on hold last year prior to the new congressional session. Kaminsky says the bill has a "high" likelihood of passing on the Senate floor and in the House, and then being signed into law.

"We believe the goals of PROTECT IP are important, and can be accomplished without reducing DNS security and stability through strategies such as the non-DNS remedies contained in PROTECT IP and international cooperation," they wrote.

Kaminsky, Crocker, Dagon, McPherson, and Vixie maintain that mandated DNS filtering will also breed plug-ins that allow users to access the filtered sites. And there will be a ripple effect on end users whose DNS settings get redirected, and likely unbeknown to the victim.

"Moreover, in households with shared computers, one user (say, a teenage music sharer) may redirect the DNS settings, but then those settings would carry over to when the parent later did online banking on the same computer. The teenager’s redirection also could redirect banking information and put it in jeopardy," the authors say.

A full copy of the "Security and Other Technical Concerns Raised by the DNS Filtering Requirements in the PROTECT IP Bill" is available here for download.

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