A new nonprofit has launched a free Domain Name System (DNS) service that filters malicious domains linked to botnets, phishing campaigns, and other malicious activity.

The new Quad9 DNS service built by IBM Security, Packet Clearing House, and the Global Cyber Alliance, is aimed at consumers and small- to midsized businesses, and doesn't share or resell user DNS lookup information to advertisers.

"Ninety to 95% of threats and major intrusions come by way of DNS," says Philip Reitinger, president and CEO of the Global Cyber Alliance and former deputy undersecretary for the National Protection and Programs Directorate at the US Department of Homeland Security. Quad9 blocks phishing sites that are flagged as malicious, he notes.

DNS attacks can be insidious for consumers as well as businesses. Three out of 10 companies say they've been hit with cyberattacks on their DNS infrastructure, 93% of whom suffered downtime due to the attack, according to a recent study by Dimensional Research on behalf of Infoblox. And that's just the organizations who actually detected that their DNS was hit; experts believe the actual number of DNS attacks is higher because many organizations don't know.

Quad9 isn't the first free DNS service, however. OpenDNS, now part of Cisco Systems as OpenDNS Home, was one of the first such services that filters malicious DNS traffic, for example, and Google offers its 8.8.8.8.  

DNS pioneer Paul Vixie, CEO and founder of DNS security firm FarSight Security, notes that there are actually hundreds of freebie DNS services, and not all are created equal. "There are hundreds of DNS service providers offering free service, but the only ones I'm sure I would trust to see my DNS lookups are Google's 8.8.8.8 and Cisco Umbrella's OpenDNS. And now, add DCA/PCH/IBM's Quad9 to that list, because their credentials are also quite strong."

While Google's 8.8.8.8 does not filter DNS responses, Cisco Umbrella's OpenDNS and Quad9 filter "any known-dangerous DNS data that could otherwise lead to a malware infection or worse," he notes.

Vixie says networks, including home networks, should opt for a DNS service with DNS filtering as a defense from network threats. While many ISPs offer this service, if they also mine customer DNS queries, it's a privacy tradeoff, he notes.

The key is to vet a DNS service's privacy policy. "Even if they publish a 'privacy policy,' they might not be following it. You need solid reason to trust a DNS service's credentials," he says.

How Quad9 Works

Setting up the Quad9 service entails reconfiguring the DNS setting on networked devices to 9.9.9.9. When a user types an URL into his or her browser, or clicks on a website, the service checks it against IBM X-Force's threat intelligence database, as well as nearly 20 other threat intelligence feeds including Abuse.ch, the Anti-Phishing Working Group, F-Secure, Proofpoint, and RiskIQ.

John Todd, executive director of Quad9 and a former Senior Technologist, Packet Clearing House, says consumers are the initial target for the new service, especially for their Internet of Things devices.

The DNS filtering service would block an IoT device from becoming a bot in a botnet such as Mirai, for example, notes Paul Griswold, director strategy and product management, IBM X-Force. "The best way to protect them [IoT devices] is through the network layer and through the DNS. So if an IoT device gets infected like they did with Mirai, it would cut off those [DNS] requests then they try to join a botnet."

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